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25 Gbps low-voltage hetero-structured
silicon-germanium waveguide pin photodetectors for monolithic
on-chip nanophotonic architectures
Daniel Benedikovic, Léopold Virot, Guy Aubin, Farah Amar, Bertrand Szelag,
Bayram Karakus, Jean-Michel Hartmann, Carlos Alonso-Ramos, Xavier Le
Roux, Paul Crozat, et al.
To cite this version:
Daniel Benedikovic, Léopold Virot, Guy Aubin, Farah Amar, Bertrand Szelag, et al.. 25 Gbps
low-voltage hetero-structured silic germanium waveguide pin photodetectors for monolithic
on-chip nanophotonic architectures. Photonics Research, OSA Publishing, 2019, 7 (47), pp.437-444.
�10.1364/PRJ.7.000437�. �hal-02543320�
25 Gbps low-voltage hetero-structured
silicon-germanium waveguide pin photodetectors for
monolithic on-chip nanophotonic architectures
D
ANIEL
B
ENEDIKOVIC
,
1,*
L
ÉOPOLD
V
IROT
,
2
G
UY
A
UBIN
1
,
F
ARAH
A
MAR
1
,
B
ERTRAND
S
ZELAG
2
,
B
AYRAM
K
ARAKUS
2
,
J
EAN
-M
ICHEL
H
ARTMANN
2
,
C
ARLOS
A
LONSO
-R
AMOS
1
,
X
AVIER
L
E
R
OUX
1
,
P
AUL
C
ROZAT
1
,
E
RIC
C
ASSAN
1
,
D
ELPHINE
M
ARRIS
-M
ORINI
1
,
C
HARLES
B
AUDOT
3
,
F
RÉDÉRIC
B
OEUF
3
,
J
EAN
-M
ARC
F
ÉDÉLI
2
,
C
HRISTOPHE
K
OPP
2
AND
L
AURENT
V
IVIEN
1
1
Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, C2N - Palaiseau, 91120 Palaiseau, France
2University Grenoble Alpes and CEA, LETI, Minatec Campus, F-38054 Grenoble, Grenoble Cedex, France 3
Technology R&D, STMicroelectronics SAS, 850 rue Jean Monnet – 38920 Crolles, France *Corresponding author: daniel.benedikovic@c2n.upsaclay.fr
Received XX Month XXXX; revised XX Month, XXXX; accepted XX Month XXXX; posted XX Month XXXX (Doc. ID XXXXX); published XX Month XXXX
Near-infrared (near-IR) Germanium (Ge) photodetectors monolithically integrated on top of silicon-on-insulator (SOI) substrates are universally regarded as key enablers towards chip-scale nanophotonics, with applications ranging from sensing and health monitoring to object recognition and optical communications. In this work, we report on the high-data-rate performance pin waveguide photodetectors made of lateral hetero-structured Silicon-Germanium-Silicon (Si-Ge-Si) junction operating under low reverse bias at 1.55 µm. The pin photodetector integration scheme considerably eases device manufacturing and is fully compatible with complementary metal-oxide-semiconductor (CMOS) technology. In particular, the hetero-structured Si-Ge-Si photodetectors show efficiency-bandwidth products of ~9 GHz at -1 V and ~30 GHz at -3 V, with a leakage dark-current as low as ~150 nA, allowing a superior signal detection of high-speed data traffics. A bit-error-rate of 10-9 is achieved for conventional
10 Gbps, 20 Gbps and 25 Gbps data rates, yielding optical power sensitivities of –13.85 dBm, –12.70 dBm, and – 11.25 dBm, respectively. This demonstration opens up new horizons towards cost-effective Ge pin waveguide photodetectors that combine fast device operation at low voltages with standard semiconductor fabrication processes, as desired for reliable on-chip architectures in next generation nanophotonics integrated circuits. © 2018 Optical Society of America http://dx.doi.org/10.1364/AO.99.099999
1. INTRODUCTION
In order to meet the increasing demands of the information-driven society, various levels of communication systems call upon components able of handling dense data streams. Indeed, recently adopted copper-based interconnects, with their inferior electronic and thermal properties, cannot fully satisfy future data traffic requirements of cloud and data center industries in terms of bandwidth, speed, energy consumption, and cost [1-5].
Silicon nanophotonics, notably on silicon-on-insulator (SOI) substrates [5-8], has emerged as a promising platform to overcome
deficient data traffic flows in on-chip interconnects [9-11]. In this field, optical photodetectors integrated on an accessible SOI technology are inevitable for myriad of applications ranging from optical communications, sensing or health monitoring to object recognition. However, silicon (Si), an indirect band-gap semiconductor with a cut-off wavelength of ~1.1 µm, is not a reliable material for photodetection at near-infrared (near-IR) wavelengths, i.e. the 1.3 – 1.55 µm spectral range historically harnessed by optical communication windows of low fiber attenuation and dispersion. To address this deficiency, rather expensive III-V compound semiconductors integrated on SOI wafers via flip-chip bonding or direct heteroexpitaxy can be used [11-13].
Ho co m A ne op low CM va en [2 co pr V be int ar ab re Ad su for dir Ex sh by T re po flo ph off I we ph he fab ac ba cu dia sp er of pr –1
2.
Fig ph Ge ph ins wa re by in tar tw Th co owever, such an omplexity and po etal-oxide-semic As an alternative, ear-IR light detec ptical absorption w-cost integratio MOS foundries. G arious growth pr nvisioned in near 6, 27]. Such com omplex functiona rospects for nano Various types of een investigated tegration scheme re implemented d bsorption losses,quisite for com dditionally, specif uch structures. Co rmation on heav rectly on Ge h xperimental reali hown convincing y III-V epitaxial he The ideal pin
sponsivity (quan ower consumptio ow available in hotodetector arch ffs are definitely n n the spirit of o e report here hotodetectors w eterojunction. The
brication and yie chieve a low-bias andwidth produc urrent leakage lo
agram show the peed signal trans rror-free operatio f 10-9 is obtained
roviding received 11.25 dBm, respe
. PIN
PHOTO-gure 1(a) show hotodetector form ermanium-Silicon hotodetectors ar sulator (SOI) wa aveguides and 2-gion (i-Ge), servi y the thickness an Fig. 1(a), the int rget thickness of wo Si slabs, with p he whole is pos oupling injection o
integration typic ssibly some cont onductor (CMOS germanium (Ge) ction [14-16, 29-, good crystallin on scheme that l Good quality Ge-b rocesses [17-23]. r-IR photodetecto mponents should alities in all gr oelectronics [28], waveguide-integ [29-46], since th e [29-41], where directly on the G however. The mpetitive photo fic Ge technologic onversely, integr vily-doped Ge reg have been prop izations of Si-con device performa eterostructures. waveguide pho ntum efficiency) on, preferably w n photonic foun hitectures that ar needed. ur previous pro on high-data-ra with a lateral Sil e butt-waveguide lds improved dev s pin photodete ct of ~9 GHz at -1 ower than 150 ability of Si-Ge-Si smissions up to on, herein reporte d for data rates o d power sensitivit ctively.
-DIODE DESIG
ws a cross-sectio med by a lateral (a n (Si-Ge-Si) heter re implemented aveguide platfor -µm-thick buried ing as an absorp nd the width (hGe trinsic Ge region f about 60 nm,p-type (p-Si) and
sitioned at the e of light inside the
cally comes with tamination of the ) pilot lines. ) has appeared as -46]. Ge’s appeal e quality, and m leverages proces based material c The use of Ge-b ors, lasers [24, 2 d ease the monol roup-IV nanopho
as well. grated Ge pin ph he early 2000s.
both doping and Ge layer, suffers
device photo-re onic receivers,
cal steps are man ration strategies t gions and the use posed and demo ntacted Ge pin ph nces, approachin otodetector shou ), a fast respons with an easy to i ndries. Therefor re not curtailed b of-of-concept de ate operation o licon-Germanium e-coupling integr vice performance ctor operation, w V bias, ~30 GHz nA. In addition, i photodetectors 40 Gbps. Last, b ed for the first tim of 10 Gbps, 20 G ties of –13.85 dBm
GN AND FABR
onal view of th across the horizo rojunction. The ge
here on a sta rm, with 220-nm oxide (BOX) laye ption medium, is × wGe) of the Ge l
is situated in a c and laterally san d n-type (n-Si) do end of the Si wa e photo-detector. h added fabricati e Si complementa s a prime choice f l comes from hi most importantly sses and tools of can be obtained v based alloys can
5] and modulato lithic integration otonic chips, wi hotodetectors ha The homojuncti d metal via-contac from a deleterio esponsivity, a co is then reduce ndatory to fabrica that avoid juncti e of metal via-plu onstrated [42-4 hotodetectors ha ng the standards s
uld have a hi se, and a reduc mplement proce re, advanced p by traditional trad monstrations [4 of pin wavegui m-Silicon (Si-Ge-ration facilitates t es. In particular, w with an efficienc z at -3 V and a dar the close-up ey of preserving hig but not least, a b me, reaching a lev Gbps, and 25 Gbp m, -12.70 dBm, an
RICATION
he pin wavegui ontal x-axis) Silico ermanium (Ge) p andard silicon-o m-thick silicon ( ers. The intrinsic inherently defin layer. As illustrat avity (hSeed), with
ndwiched betwe pings, respective aveguide for bu on ary for igh y, a f Si via be ors of ith ave on cts ous ore ed. ate on ugs 6]. ave set igh ced ess pin de-6], ide Si) the we cy- rk- ye- gh- bit-vel ps, nd ide on-pin on-Si) Ge ned ted h a een ely. Fig. 1. ( with a l profile o thick an view (y and 40-as obtai injected The p yield th microm µm × 1 transve wavelen fundam optical specifica region p while a and n-t facilitate differen to the c optical d the fun decreas doped r light fr polarize injection coupling integrat intensit dimens [47], al photode efficient Ge zone The in lateral p compac approac (a) Transversal s lateral Si-Ge-Si h of the fundamen nd 1-µm-wide he
y-z plane) of the o
-µm-long butt-w ined from 3-D FD d from the Si wav photodetector tra he best device p metric area. The r 1 µm (hGe × wGe) erse electrical ( ngths. As seen i mental TE mode, power occupie cally, numerical c provides an exce a comparatively l type doped Si r ted by the enha nce between the G conventional Ge design reduces th ndamental TE m sing absorption l
regions. Furtherm rom the injectio
ed mode in the de n waveguide and ng efficiency). Fi ted butt-wavegu ty distribution, ional (3-D) Fini long the centra etector is an exte tly transferred fr e. ntegration strateg pin hetero-juncti ct photodetectors ch substantially schematics (x-y p heterojunction ar ntal TE-polarized eterostructured p optical intensity waveguide-couple DTD simulations veguide on the left
ansversal dimens performances po resulting device c ) in order to hav (TE) modes at in the calculated shown in the in es almost com calculations sugg essively large pow
ow power of onl regions. The im anced lateral in Ge core and the S pin homojunctio he overlap betwe mode and lossy
osses from phot more, this also e on Si waveguide
evice. The estima d the Ge photod igure 1(b) pres uide-coupled pin as modeled w ite-Difference Ti al plane of the ension of the Si w rom the injection gy, combining bu ion configuration s with properly e eases photodet
lane) of the pin p rchitecture. Inset d optical mode in photodetector. (b) distribution in th ed pin Si-Ge-Si p . The fundament ft-hand-side.
sions have been ossible within a
configuration wa ve an efficient p C-band (aroun d electric field p nset of Fig. 1(a), mpletely the Ge gest that a 1-µm-w wer confinement ly 7% is present mproved field co ndex contrast, i Si-doped regions, on configuration een the evanesce Si-doped slabs, to-generated carr nables an efficien e into the fund ated coupling loss detector is -0.61 sents side schem n photodetector with a full-vec me Domain (FD structure. Since waveguide, the op n waveguide into utt-waveguide-co ns, facilitates the engineered waveg tector fabricatio photodetector t: Electric field n a 0.260-µm-) Longitudinal he 1-µm-wide photodetector, tal TE mode is optimized to compact sub-as set to 0.260 propagation of nd 1.55 µm) profile of the the resulting e area. More wide intrinsic of up to 87%, t in the p-type onfinement is i.e. the index , as compared [29-41]. This nt field tails of substantially riers in the Si-nt coupling of damental TE-s between the dB (~87% of matics of the with optical ctorial three-DTD) method e the Ge pin ptical power is o the intrinsic oupling and a fabrication of guide. Such an on and yields
im op en do It ma inv pa ph ste T be ph pr co su ult ox im Bo de ox pa flo gr – C lon re su for pa wa Ti/ pa
3.
A. Co an pin las op su wa to nm wa ph I ph ph da de len of th to an re yie lon re mproved device p pto-electrical ban nables to fabricat oped Si, which ar should also be m ature manufactu volved in the fab aving the way fo hotonic componeeps and thus cost The pin photode een fabricated in hotonic platform rocesses, as det omponents, inclu urface grating co traviolet (deep-U xidation has been mplantation. The p oron and Phosph eposited prior to xide has been et atterning and dee oors above the BO rown with GeH4 in
Chemical Vapor D ng annealing at 7
duce the Ge film urface. Afterward
r Ge passivation atterned and etch as then conduc /TiN/W stack w atterned AlCu lay
. DEVICE EXPE
Static current-v
onventional static nd light-illuminat
n photodetectors ser has been coup ptical fiber (SMF-urface grating cou
avelength of 1.55 short single-mod m-wide transver aveguide photod hotodetectors we I-V characteristics hoto-current (I hotodetectors, ar ark-currents, 7 n evices. The dark ngth. The inset of f the device junct is evolution sugg the bulk leakag nd 40 µm-long ph spectively, (for a elds moderate d ngest devices. Th ports on Si-conta performances in ndwidth [43, 44, 4
e the metallic con e robust steps in mentioned that uring steps, such brication of optic
r monolithic inte ents with a signif
t. etectors with a la CEA-LETI’s clean m with 200 mm tailed in Ref. [ uding interconnec ouplers, have be UV) photo-lithog n performed to
p-type and n-typ
horous ion implan o the cavity pat tched down to t ep-rib etching to OX. A more than n those cavities v Deposition (RP-C 750⁰C and Chem m thickness dow s, a few-µm-thick and insulation. hed down to Si d cted to improve were used as me er.
ERIMENTS: R
voltage measure c current-voltage ted conditions, ha s. More specifical pled into the Si ch-28). Optical inter uplers, optimized 5 µm. The surfac de Si strip waveg rsal geometry, detector through ere biased using a s of the leakage d
Ip), in 1-µm-w
re shown in Fig. 2 nA under low-bia k-current increas
f Fig. 2(a) shows d tion area at -1 V gests that the sur ge. In addition, th hotodetectors are a bias of -1 V). Fu dark current incr
he measured valu acted pin wavegu
n terms of photo 46]. In particular ntacts directly on n comparison to m
the very same m h as ions impla cal modulators o egration of both ficantly reduced n ateral Si-Ge-Si he nroom facilities o m SOI wafers an [46]. First, pass cting waveguide een fabricated v graphy and dry have a SiO2 cap
pe Si regions have ntation. An oxide tterning. Sub-seq the Si surface, fo form cavities wit n 1 µm Ge layer w via 450⁰C / 750⁰C CVD) process, foll mical Mechanical wn to ~260-nm k oxide cladding h 400-nm × 400-n doped regions. N e contact resista
etal plugs. Electr
RESULTS AND
ements
e (I-V) measurem ave been perform lly, the light com hip through a sta rfacing has been d for a TE polariz ce grating couple guides, with 220-delivering light butt-coupling sc an electrical prob dark-current (Id) wide by 40-2(a). Measured d as conditions (-1 ses monotonousl dark-current evo V bias. The linear rface leakage is ne he dark-currents e equal to 19 nA, urther increases rease, up to 150 ues compare fav uide photodetecto
o-responsivity an r, such an approa n n-type and p-ty metallization on G masking levels an antation in Si, a on Si platform [2 passive and acti number of proce eterojunction ha on a fully integrat nd standard CMO sive nanophoton s and fiber-to-ch via 193-nm dee y etching. Therm layer prior to i e been obtained e cladding has be quently, the upp ollowed by Si fil th ~60-nm-thick was then selective C Reduced Pressu lowed by a 1-hou Polishing (CMP)
and recover a f has been deposit nm vias have be Ni-based silicidati ance. At the en rodes consisted
DISCUSSION
ments, under dar med on the Si-Ge ming from a tunab
andard single-mo n realized thanks zation and a centr ers were connect
-nm-thick and 50 into the Ge p cheme. The on-ch
e.
and the generat µm-long Si-Ge devices exhibit lo 1 V) for 5-µm-lo ly with the devi olution as a functi trend observed egligible compar for 10 µm, 20 µ 43 nA, and 100 n of reverse volta nA at -4 V for t vorably to previo ors [42-46] and a nd ach ype Ge. nd are 7], ive ess ave ted OS nic hip ep-mal on by en per lm k Si ely ure ur-to flat ted een on nd, in
NS
rk- -Si ble de to ral ted 00-pin hip ted -Si ow ng ice on in red µm nA, age the ous are substan micro-m domina governs main d hetero-s current high-sp establis Fig. 2. ( 40-µm-l illumina of devic respons lengths.ntially lower tha metric cross-sect ating at low elect s carriers genera dark-current con structured Si-Ge ts substantially lo peed and low-p shed SOI nanopho
(a) Static current long hetero-stru ated states. Inset ce junction area. sivity as a functi . (c) Quantum eff
an that of pure tional areas [29 tric fields, and b ation at moderat ntributors. In ag e-Si pin photodet
ower than 1 µA [ power consump otonic platform.
t-voltage (I-V) ch uctured pin phot t: Leakage dark-c Photodetectors w ion of the revers ficiency as a funct homo-junction -41]. Trap-assist band-to-band tun te/high electric f greement with tectors provide l [16], making them ption photonic haracteristics of 1 todetector, in da current evolution were biased at -1 se voltage for dif tion of the device
devices with ted tunneling, nneling, which fields, are the expectations, leakage dark-m suitable for receivers in 1-µm-wide by ark- and light-n as a fulight-nctiolight-n 1 V. (b)
Photo-fferent device e length under
-0 eff T as th th co inc Th es po 0.2 F a ph lon re ph pin low be ind be re pr de ph ca A ult wh th (5 rev is wa re 4% Si-inc cu B. To str fre co (L I-V lig pin tee ca co ex tra F th wa in th wa .5 V reverse bias ficiencies for an e The responsivity the ratio betwe e net-light curre e leakage dark orresponds to th cluding the inser he optical power timated to be -ower uncertainty 24 dB. Figure 2(b) show function of the hotodetector resp ngest (40-µm-lo spectively, amon hotodectors [42-4 n waveguide pho w as -0.5 V, one o ehavior is con dependently on eyond a -0.5 V b mains virtually resence of the emonstrates the hotodetectors to arriers (electron-h As a consequence tra-high quantum here λ is the oper e quantum efficie -µm-long) up to verse bias. In oth
sufficiently long aveguide. In addi sults in changes i %. This also conf -Ge-Si heterojun cident photons i urrent.
Small-signal rad
o assess the opt ructured Si-Ge-Si equency (RF) me onventional RF-te LCA), with interna
V measurements,
ght signal into the n waveguide pho e using a Keithle alibrations of the ontributions fro xperiments were ansmission param Figure 3(a) show
e small-signal aveguide photod a range from 0 V e photodetector as measured at a . The shadowed estimated power of the photodete en the generated ent, i.e. a photo-c k-current) and t
he received pow rtion loss of the r coupled into t 11.2 dBm in th y associated with ws the photo-resp reverse voltage ponsivity at -1 V f ong) devices a ng the highest val 46]. As shown in otodetectors reac of the lowest rev nsistently observ
the device length bias, the device
flat, with a ne strong built-in
outstanding ca sweep out the va holes pairs) withi e, Si-Ge-Si hetero m efficiency (η), rating wavelengt ency increases fr ~95% for the lo her words, this su g to absorb a 95
ition, the estimate in quantum effici firms the superio nction photodete into electrons co dio-frequency m to-electrical ban i photodetectors, easurements. Exp est set-up with ally-built laser an
, the optical inter e Si chip calls up otodetectors wer ey Source Measu e RF path was ca om cables and e performed by meter in the LCA ws a set of S21 freq
RF measureme detector. The devi V to -4 V, using a of -11 dBm. The a bias of 0 V. Inde region denotes a uncertainty of +/ ector (R = Ip/Pi), h d photo-current current without t
the input optic wer that reache fiber-chip surfac the waveguide p ese measuremen this estimation is ponsivity of a 1-µm e for different d
for the shortest (5 are 0.19 A/W
lues reported so n Fig. 2(b), the re
ch their maxima verse bias demon ved on all m h. It is also worth responsivity rea egligible voltage electrical field a apability of hete ast majority of th in their lifetime. -structured phot defined as follow th of 1.55 µm. As rom ~14.2% for t ngest device (40 uggests that a 40 % of the incom ed power uncerta iency, with a max or collection effic ectors, i.e. the h ntributing to the measurements ndwidth propert , we carried out periments were a Lightwave Com nd modulator. Sim rfacing that deliv pon fiber-chip gra re reversely biase urement Unit. P arried out to tak d probes. The collecting the re tool as a function quency responses ents performed ice was probed a n average optica cut-off frequenc eed, the opto-elec
a range of quantu /- 0.24 dB. has been calculat
(here, Ip stands f the contribution cal power (Pi). es the photodiod ce grating coupl photodetector w nt conditions. T s the in range of + m-wide detector evice lengths. T 5-µm-long) and t and 1.19 A/W far for Si-Ge-Si p esponsivities of at bias voltages nstrated so far. Th measured devic h highlighting th aches plateau an dependence. T at low-bias stat ero-structured p he photo-generat todetectors have ws: η = (R·1.24)/ shown in Fig. 2( the shortest devi -µm-long) at -0.5 -µm photodetect ing light in the ainty of +/- 0.24 d ximum range of + ciency of lateral p high conversion
e generated phot
ties of the heter small-signal rad performed using mponent Analyz milarly to the sta vers the modulat ating couplers. T ed thanks to a bia rior to testing, t ke into account t small-signal R esponse of the S n of frequency. s, as retrieved fro on Si-Ge-Si p at various bias sta al power coupled cy of only ~1.8 GH ctrical bandwidth um ted for of Pi de, er. was The +/- as The the W, pin Ge as his es, hat, nd The tes pin ted an /λ, (c), ice 5 V tor Ge dB +/- pin of to- ro- io-g a zer atic ted The as-the the RF S21 om pin ate to Hz h is limited carriers collecte relative Fig. 3. (a µm-wid under d traces o at -1 V. device bandwi photode
under the zero-b s. In that case, ed only by the bu ely weak under su
a) Small-signal R de by 40-µm-lon different bias con of different length
(b) Opto-electric lengths. (c) Pro idth versus re etectors with dif
bias state. This is photo-generated uilt-in electric fiel
uch biasing condi
RF measurements ng hetero-struct nditions in a range
h Si-Ge-Si pin wav cal bandwidths ve oduct of the qu everse bias fo fferent lengths. T
due to the long t d carriers can ld, which strength itions [46]. s of the S21 respo tured Si-Ge-Si p e from 0 V to -4 V veguide photodet ersus reverse bia uantum efficienc or Si-Ge-Si pin The shadowed re transit time of be efficiently th is, however, onses of the 1-photodetector, V. Inset: S21 RF tectors biased as for different cy by the RF n waveguide egions denote
ra un T at op to bia yie Sp ~1 re ele tre fre be ins lim F op rev ex lon zo fur va Th pr op C. bit Th ph m ac rat op (P 25 wa do sp co m co m co Si am ret tes of RF dia 38 an 10 BE sh ca ph anges of efficien ncertainty of +/- 0 Those results are
zero-bias. Such peration of a hete pure Ge photode as, the enhanced elds an increase pecifically, as sum
13 GHz at -1 V r ached. For highe ectrical bandwid ends have been equency of the ecomes roughly i set of Fig. 3(a), w mited by the RC d Figure 3(c) show pto-electrical RF b verse bias, for di xpected, the highe
ngest photodetec one. The efficienc rther raises to 30 ariation of +/- 2.3 hese achievemen romising to simu peration. Large-signal da t-error-rate asse he high-speed hotodiodes was easurements. Ex cquisitions and in ate (BER) testing. ptical modulatio PRBS) data patter 5, 28, 32, and 40 as 1.55 µm. The oped fiber amplif pontaneous emi ontrolled thanks t eter. Optical TE ontroller to opti odulated signal w oupler, followed b pin photodetect mplifier (TIA) or trieved through sting, by applying f a RF probe conn F bias-tee output agrams. BER ass 8-GHz-broadband nd the BER detec 00 mV peak-to-pe ER, for different t hown in Fig. 4 an arried out in a hotodetector. ncy-bandwidth p 0.24 dB. e also consistent w h a behavior set ero-structured Si etectors [29-41]. d electric field pr
of both the cut-mmed up in Fig. 3 reverse bias, whil er reverse biases dth further incre n observed for a e hetero-structu independent on t with a -1 V bias, delay. ws the product o bandwidth, label ifferent Ge pin w est efficiency-ban ctor configuration cy-bandwidth pro 0 GHz for a -3 V GHz for a previo nts show that ultaneously have ata measuremen essments operation of further investiga xperiments cons nput power sens Data were trans on format. The rn 27-1 was cons
0 Gbps. The exter transmitted sign fier (EDFA), follo ission noise. Th to a variable optic E polarization w
imize the inten was sent into the by on-chip detect tor, without the
on-chip limiting the RF set-up p g the reverse bia nected to a bias-te
to a high-speed s sessments were p d electrical ampli ction module, wh eak signal voltag transmission rat nd Fig. 5, respect 1-µm × 40-µm
product for an
with the observe ts practical limi i-Ge-Si photodete Conversely, with resent inside the off frequency an 3(b), the cut-off f le at -2 V, a ~24 s of -3 V and -4 V eases up to ~32 all measured de ured Si-Ge-Si pi the device length i.e. the measured of the quantum led as QE × BW, a waveguide photod ndwidth product n, i.e. with a 40-µ oduct is around reverse voltage, ously introduced Si-Ge-Si pin p e high responsivi nts: Eye-diagram hetero-structur ated by perform sisted in eye-dia sitivity assessme mitted in non-re pseudo-random sidered for differ
rnally modulated nal was amplifie owed by an opti he average op cal attenuator an was adjusted w nsity of the det e Si chip thanks t tion in the heter use of integrated amplifier (TA). E previously used f as to the photode ee. Data were dir sampling oscillos performed by ins ifier between the hose minimum le ge. The measured tes and various b tively. Large-signa (Ge width × G
estimated pow
ed low responsiv its for a zero-bi ector, as compar h increasing rever e intrinsic Ge zo nd the responsivi frequency becom 4 GHz bandwidth V, the device opt GHz. Comparab evices. The cut-in photodetecto hs, as shown in t d bandwidth is n efficiency and t as a function of t detector lengths. t is achieved for t µm-long intrinsic 9 GHz at -1 V an with an estimat power uncertain photodetectors a ity and high-spe
m acquisitions an
red Si-Ge-Si p ming data detecti
agram large-sign ents with bit-erro turn-to-zero (NR m-binary-sequen ent rates of 10, 2 d laser waveleng
d with an Erbium ical filter to redu ptical power w d an in-line powe with a polarizati tected signal. T to a surface grati o-structured Si-G d trans-impedan Electrical data we for small-signal R etector with the u
rectly sent from t scope, depicting e serting an extern e RF bias-tee outp evel requirement d eye diagrams an bias conditions, a al data testing w Ge length) Si-Ge wer vity ias red rse ne ity. mes h is to-ble off ors the not the the As the Ge nd ted nty. are eed nd pin on nal or-RZ) nce 20, gth m-uce was er-on The ing Ge-nce ere RF use the eye nal put t is nd are was -Si In agre closed a behavio reverse clear op field w opened Gbps, 2 V, enabl suggest 2 V bias bandwi data rat high-bit Fig. 4. E range a Here, x vertical 40-µm ( Fig. 5( optical conditio are equ Fig. 5(b Gbps, 2 sensitiv associat penalty Gbps is with a b bandwi
eement with sma at 0 V bias, as s or has also bee e bias increase (-0
pening of the eye within the intrin
d eye diagrams a 0 Gbps, and 25 G ling BER examin t that high-speed asing up to 40 Gb
idth at -1 V bias te increases. Yet t-rate signals dete
Evolution of eye at 10 Gbps, 20 Gb
x [ps/div] and y
scope axis withi (Ge width × Ge le (a) shows BER
power for a 10 G ons. Optical pow ual to –9.95 dBm b) shows the me 20 Gbps, and 25 vities of –13.85 ted to those data y measured when attributed to the better suited elec idth. Lower pea
all-signal RF mea shown in Fig. 4 en observed for 0.5 V and -1 V at e diagram, becau nsic region, as e are obtained for Gbps, with revers nation. Additional signal detection i bps data speeds. explains why ey t, the voltage adj ection capability diagram apertu bps, 25 Gbps, 28 y [mV/div] corre in the particular ength) Si-Ge-Si ph measurements a Gbps data rate, u wer sensitivities, d m, –12.75 dBm an easured BER for
Gbps under -3 V dBm, –12.70 a rates. It is wort n the bit rate incr e fact that sensitiv
ctrical error detec ak-to-peak signal
asurements, the e for a 10 Gbps d other transmis t 10 Gbps line rat use of the genera
explained previo conventional dat se voltages of -1 V lly, eye diagram a is potentially ach . The restricted p ye diagrams are c justment possibi
up to 40 Gbps.
ures within a low 8 Gbps, 32 Gbps, espond to the h measurement se hotodetector. as a function of under -1 V, -2 V defined as yieldin nd –13.85 dBm f transmission dat V bias. BER 10-9 o dBm and –11. th noting that the
reases from 10 G vity at 10 Gbps sh
ction chain with l voltage requir
eye diagram is data rate. This ssion rates. A te) results in a ated electrical ously. Clearly ta rates of 10 V, -2 V, and -3 apertures also hievable from -photodetector closing, as the ility preserves w-reverse-bias and 40 Gbps. horizontal and etting. 1-µm × f the received and -3 V bias ng a 10-9 BER,
for those bias. ata rates of 10 optical power 25 dBm are e low induced Gbps up to 20 hould be lower a much lower ement at the
er we Fig ph as an µm
4.
In ph pe de co de su str rror detection m ell. g. 5. Bit-error-ra hotodetector as sessments perfo nd (b) at 10 Gbps, m (Ge width × Ge. CONCLUSIO
summary, we hotodetectors w erformances, whe evices strongly b oupling with late evices with a ubstantially impructured pin wa
module input sho
ate measuremen a function of ormed (a) at 10 G , 20 Gbps, and 25 length) Si-Ge-Si p
NS
have experimen with lateral Si en operating und benefit from the eral Si-Ge-Si pin definitely redu roved performa aveguide photodeould decrease se
nts of the Si-Ge-f the input opt Gbps under low-5 Gbps, all biased photodetector. ntally shown th -Ge-Si junction der low-reverse-b e combination o n junctions, res uced fabrication ances. More sp etectors yield eff
ensitivity values
-Si pin wavegui tical power. BE -reverse-bias stat
at -3 V. 1-µm × 4
hat pin wavegui s have superi bias at 1.55 µm. T of butt-waveguid ulting in compa n complexity an pecifically, heter ficiency-bandwid as de ER tes 40-ide ior The de-act nd ro-dth product than 15 photode A bit-er 20 Gbps 12.70 d promisi efficient ultimate architec Fundin (ERC PO
Refere
1. L. Vivi 2. M. As Nat. 3. D. Tho Marr Schm Nede 4. K. Yam Y. Ish phot Adv. 5. X. Che Li, D. Phot (2018 6. R. Hal Wan “Sub Devic 7. J. Chill Opt. 8. D. Ma M. M Chras phot 1781 9. Y. Li, Y on hy of the 10. A. V. circu Quan 11. G. Ro V/sili Phot 12. O. M “Hete (2018 13. T. Ko Bowe on Si 14. S. Fa perfo comm 15. S. J. K infrar Quan 16. J. Mi phot ts of ~9 GHz at -50 nA. Eye dia etectors enable a rror-free operatio s, and 25 Gbps, w dBm, and –11.25 ing prospects fo t and low-cost ely could usher ctures in optical inng Information.
OPSTAR – grant a
ences
ien and L. Pavesi, H sghari and A. V. Kris Photonics 5, 268-2 omson, A. Zilkie, J. ris-Morini, E. Cassa mid, D.-X. Xu, F. Boe
eljkovic, “Roadmap mada, T. Tsuchizaw hikawa, K. Wada, a tonics technology f Mater. 15, 024603 en, M. M. Milosevi J. Thomson, F. Ga tonics as a Flexible 8). lir, A. Ortega-Moñu güemert-Pérez, J. bwavelength-Gratin ces,” P IEEE 106, 21 les and S. Fathpou
19, 053001 (2017)
arris-Morini, V. Vak Montesinos, C. Alon stina, L. Vivien, and tonics from near- to 1-1793 (2018). Y. Zhang, L. Zhang,
ybrid silicon photo e art and perspect . Krishnamoorthy a
its into the 21st ce ntum Electron. 22, oelkens, L. Liu, D. L icon photonics for ton. Rev. 4, 751-77 Marshall, M. Hsu, Z. erogeneous Integr 8).
omljenovic, D. Hua ers, “Photonic Inte ilicon,” P IEEE 106, ama, L. Colace, G. M
ormance germaniu munications,” App Koester, J. D. Schau red detectors for in ntum Electron. 12, ichel, J. Liu, and L. C todetectors,” Nat. P
-1 V, ~30 GHz at agram inspection a detection of high on of 10-9 is achie
with optical powe 5 dBm, respective for the developm
t photodetector a future genera ntegrated circuit H2020 Europea agreement No 64 Handbook of Silicon shnamoorthy, “Ene 270 (2011). E. Bowers, T. Kom an, L. Virot, J.-M. Fé euf, P. O’Brien, G. Z p on silicon photon wa, H Nishi, R. Kou, nd T. Yamamoto, “ for telecommunica 3 (2014).
c, S. Stankovic, S. R rdes, and G. T. Ree Technology Platfo ux, D. Benedikovic, H. Schmid, Í. Molin ng Metamaterial St 144-2157 (2018). ur, “Silicon photonic
). karin, J. M. Ramirez nso-Ramos, X. Le R d G. Isella, “Germa o mid-infrared app and A. W. Poon, “S onic devices for intr
tives,” Photon. Res and D. A. B. Miller, entury: A technolog
55-76 (1996). Liang, R. Jones, A. F
on-chip and intra-9 (2010). . Wang, B. Kunert, ration on Silicon Ph ng, P. Pintus, M. A egrated Circuits Usi 2246-2257 (2018) Masini, G. Assanto, um-on-silicon dete pl. Phys. Lett. 81, 58 ub, G. Delinger, an ntegrated photoni 1489-1502 (2006) C. Kimerling, “High Photonics 4, 527-5 t -3 V and dark-cu ns confirm that gh-speed signals u
eved for data rate er sensitivities of – ely. This demons ment of high-sp rs at the chip-ation of silicon n ts. an Research Cou 47342). n Photonics (CRC P ergy-efficient com ljenovic, G. T. Reed édéli, J.-M. Hartma Z. Mashanovich, an nics,” J. Opt. 18, 07 T. Hiraki, K. Taked “High-performance ations applications, Reynolds, T. Domin ed, “The Emergenc orm,” P IEEE 106, 21
, G. Z. Mashanovic na-Fernández, and
tructures for Silico cs beyond silicon-o z, Q. Liu, A. Ballabio Roux, S. Serna, D. B
anium-based integr plications,” Nanoph Silicon and optical ra-datacenter appl s. 3, B10-B27 (2015 “Scaling optoelect gy roadmap,” IEEE Fang, B. Koch, and J chip optical interco C. Koos, and D. Va hotonics,” P IEEE 10 A. Tran, M. L. Daven ing Heterogeneou ). , and H.-C. Luan, “H ctors for optical 86-588 (2002). nd J. O. Chu, “Germ ic applications,” IEE ). h-performance Ge-534 (2010). urrents lower t Si-Ge-Si pin up to 40 Gbps. es of 10 Gbps, –13.85 dBm, – stration holds peed, energy--scale, which nanophotonic uncil (ERC) – Press, 2013). munication,” d, L. Vivien, D. ann, J. H. nd M. 3003 (2016). da, H. Fukuda, e silicon ,” Sci. Technol. nguez-Bucio, K. ce of Silicon 101-2116 ch, J. G. P. Cheben, n Photonic on-insulator,” J. o, J. Frigerio, enedikovic, D. rated hotonics 7, receiver based ications: state 5). tronic-VLSI J. Sel. Top. J. Bowers, “III-onnects,” Laser an Thourhout, 06, 2258-2269 nport, and J. E. s Integration High manium-on-SOI EE J. Sel. Top. -on-Si
17. T. A. Langdo, C. W. Leitz, M. T. Currie, E. A. Fitzgerald, A. Lochtefeld, and D. A. Antoniadis, “High quality Ge on Si by epitaxial necking,” Appl. Phys. Lett. 76, 3700-3702 (2000).
18. J. M. Baribeau, T. E. Jackman, D. C. Houghton, P. Maigné, and M. W. Denhoff, “Growth and characterization of Si1-xGex and Ge epilayers on (100) Si,” J. Appl. Phys. 63, 5738–5746 (1988).
19. H.-C. Luan, D. R. Lim, K. K. Lee, K. M. Chen, J. G. Sandland, K. Wada, and L. C. Kimerling, “High-quality Ge epilayers on Si with low threading-dislocation densities,” Appl. Phys. Lett. 75, 2909–2911 (1999). 20. C. G. Littlejohns, M. Nedeljkovic, C. F. Mallinson, J. F. Watts, G. Z.
Mashanovich, G. T. Reed, and F. Y. Gardes, “Next generation device grade silicon-germanium on insulator,” Sci. Rep. 5, 8288 (2015).
21. C. G. Littlejohns, T. Dominguez Bucio, M. Nedeljkovic, H. Wang, G. Z. Mashanovich, G. T. Reed, and F. Y. Gardes, “Towards a fully functional integrated photonic-electronic platform via a single SiGe growth step,” Sci. Rep. 6, 19425 (2016).
22. J.-M. Hartmann, J.-F. Damlencourt, Y. Bogumilowicz, P. Holliger, G. Roland, and T. Billon, “Reduced pressure-chemical vapor deposition of intrinsic and doped Ge layers on Si(001) for microelectronics and optoelectronics purposes,” J. Crys. Growth 274, 90-99 (2005). 23. Y. H. Tan and C. S. Tan, “Growth and characterization of germanium
epitaxial film on silicon (001) using reduced pressure chemical vapor deposition,” Thin Solid Films 520, 2711-2716 (2012).
24. J. Liu, X. Sun, R. Camacho-Aguilera, L. C. Kimerling, and J. Michel, “Ge-on-Si laser operating at room temperature,” Opt. Lett. 35, 679-681 (2010). 25. R. E. Camacho-Aguillera, Y. Cai, N. Patel, J. T. Bessette, M. Romagnoli, L. C.
Kimerling, and J. Michel, “An electrically pumped germanium laser,” Opt. Express 20, 11316-11320 (2012).
26. G. T. Reed, G. Mashanovich, F. Y. Gardes, and D. J. Thomson, “Silicon optical modulators,” Nat. Photonics 4, 518-526 (2010).
27. D. Marris-Morini, L. Virot, C. Baudot, J.-M. Fédéli, G. Rasigade, D. Pérez-Galacho, J.-M. Hartmann, S. Oliver, P. Brindel, P. Crozat, F. Boeuf, and L. Vivien, “A 40 Gbit/s optical link on a 300-mm silicon platform,” Opt. Express 22, 6674-6679 (2014).
28. A. H. Atabaki, S. Moazeni, F. Pavanello, H. Gevorgyan, J. Notaros, L. Alloatti, M. T. Wade, C. Sun, S. A. Kruger, H. Meng, K. Al Qubaisi, I. Wang, B. Zhang, A. Khilo, C. V. Baiocco, M. A. Popović, V. M. Stojanović, and R. J. Ram, “Integrating photonics with silicon nanoelectronics for the next generation of systems on a chip,” Nature 556, 349-354 (2018). 29. L. Colace and G. Assanto, “Germanium on silicon for near-infrared light
sensing,” IEEE Photonics J 1, 69-79 (2009).
30. T. Yin, R. Cohen, M. M. Morse, G. Sarid, Y. Chetrit, D. Rubin, and M. J. Paniccia, “31 GHz Ge n-i-p waveguide photodetectors on Silicon-on-Insulator substrate,” Opt. Express 15, 13965-13971 (2007). 31. L. Vivien, J. Osmond, J.-M. Fédéli, D. Marris-Morini, P. Crozat, J. F.
Damlencourt, E. Cassan, Y. Lecunff, and S. Laval, “42 GHz p.i.n germanium photodetector integrated in a silicon-on-insulator waveguide,” Opt. Express 17, 6252-6257 (2009).
32. D. Feng, S. Liao, P. Dong, N. Feng, N. Feng, H. Liang, D. Zheng, C. Kung, J. Fong, R. Shafilha, J. Cunningham, A. Krishnamoorthy, and M. Asghari, “High-speed Ge photodetector monolithically integrated with large cross-section silicon-on-insulator waveguide,” Appl. Phys. Lett. 95, 261105 (2009).
33. J. Joo, S. Kim, I. G. Kim, K.-S. Jang, and G. Kim, “High-sensitivity 10 Gbps Ge-on-Si photoreceiver operating at λ~1.55 µm,” Opt. Express 18, 16474-16479 (2010).
34. S. Assefa, F. Xia, S. W. Bedell, Y. Zhang, T. Topuria, P. M. Rice, and Y. A. Vlasov, “CMOS-integrated high-speed MSM germanium waveguide photodetector,” Opt. Express 18, 4986-4999 (2010).
35. S. Liao, N.-N. Feng, D. Feng, P. Dong, R. Shafilha, C.-C. Kung, H. Liang, W. Qian, Y. Liu, J. Fong, J. E. Cunningham, Y. Luo, and M. Asghari, “36 GHz submicron silicon waveguide germanium photodetector,” Opt. Express
19, 10967-10972 (2011).
36. C. T. DeRose, D. C. Trotter, W. A. Zortman, A. L. Starbuck, M. Fisher, M. R. Watts, and P. S. Davids, “Ultra compact 45 GHz CMOS compatible
Germanium waveguide photodiode with low dark current,” Opt. Express
19, 24897-24904 (2011).
37. L. Vivien, A. Polzer, D. Marris-Morini, J. Osmond, J. M. Hartman, P. Crozat, E. Cassan, C. Kopp, H. Zimmermann, and J.-M. Fédéli, “Zero-bias 40 Gbit/s germanium waveguide photodetector on silicon,” Opt. Express 20, 1096-1101 (2012).
38. G. Li, Y. Luo, X. Zheng, G. Masini, A. Mekis, S. Sahni, H. Thacker, J. Yao, I. Shubin, K. Raj, J. E. Cunningham, and A. V. Krishnamoorthy, “Improving CMOS-compatible Germanium photodetectors,” Opt. Express 20, 26345-26350 (2012).
39. H. Pan, S. Assefa, W. M. J. Green, D. M. Kuchta, C. L. Schow, A. V. Rylyakov, B. G. Lee, C. W. Baks, S. M. Shank, and Y. A. Vlasov, “High-speed receiver based on waveguide germanium photodetector wire-bonded to 90nm SOI CMOS amplifier,” Opt. Express 20, 18145-18155 (2012). 40. L. Virot, L. Vivien, J.-M. Fédéli, Y. Bogumilowitz, J.-M. Hartmann, F. Boeuf,
P. Crozat, D. Marris-Morini, and E. Cassan, “High-performance waveguide-integrated germanium PIN photodiodes for optical communication applications,” Photon. Res. 1, 140-147 (2013).
41. T.-Y. Liow, N. Duan, A. E.-J. Lim, X. Tu, M. Yu, and G.Q. Lo, “Waveguide Ge/Si avalanche photodetector with a unique low-height-profile device structure,” In Optical Fiber Communications Conference, OSA Technical Digest (online), (Optical Society of America, 2014), pp. M2G.6. 42. Y. Zhang, S. Yang, Y. Yang, M. Gould, N. Ophir, A. E.-J. Lim, G.-Q. Lo, Y P.
Magill, K. Bergman, T. Baehr-Jones, Y and M. Hochberg, “A high-responsivity photodetector absent metal-germanium direct contact,” Opt. Express 22, 11367-11375 (2014).
43. H. T. Chen, P. Verheyen, P. De Heyn, G. Lepage, J. De Coster, P. Absil, G. Roelkens, and J. Van Campenhout, “High-responsivity low-voltage 28-Gb/s Ge p-i-n photodetector with silicon contacts,” IEEE/OSA J. Lightwave Technol. 33, 820-824 (2015).
44. H. Chen, P. Verheyen, P. De Heyn, G. Lepage, J. De Coster, S. Balakrishnan, P. Absil, W. Yao, L. Shen, G. Roelkens, and J. Van Campenhout, “-1 V 67 GHz bandwidth Si-contacted germanium waveguide p-i-n photodetector for optical links at 56 Gbps and beyond,” Opt. Express 24, 4622-4631 (2016).
45. H. Chen, P. Verheyen, P. De Heyn, G. Lepage, J. De Coster, S. Balakrishnan, P. Absil, G. Roelkens, and J. Van Campenhout, “Dark current analysis in high-speed germanium p-i-n waveguide photodetectors,” J. Appl. Phys.
19, 213105 (2016).
46. L. Virot, D. Benedikovic, B. Szelag, C. Alonso-Ramos, B. Karakus, J.-M. Hartmann, X. Le Roux, P. Crozat, E. Cassan, D. Marris-Morini, Ch. Baudot, F. Boeuf, J.-M. Fédéli, C. Kopp, and L. Vivien, “Integrated waveguide PIN photodiodes exploiting lateral Si/Ge/Si heterojunction,” Opt. Express 16, 19487-19496 (2017).
Full reference list
1. L. Vivien and L. Pavesi, Handbook of Silicon Photonics (CRC Press, 2013). 2. M. Asghari and A. V. Krishnamoorthy, “Energy-efficient communication,”
Nature Photonics 5, 268-270 (2011).
3. D. Thomson, A. Zilkie, J. E. Bowers, T. Komljenovic, G. T. Reed, L. Vivien, D. Marris-Morini, E. Cassan, L. Virot, J.-M. Fédéli, J.-M. Hartmann, J. H. Schmid, D.-X. Xu, F. Boeuf, P. O’Brien, G. Z. Mashanovich, and M. Nedeljkovic, “Roadmap on silicon photonics,” Journal of Optics 18, 073003 (2016).
4. K. Yamada, T. Tsuchizawa, H Nishi, R. Kou, T. Hiraki, K. Takeda, H. Fukuda, Y. Ishikawa, K. Wada, and T. Yamamoto, “High-performance silicon photonics technology for telecommunications applications,” Science and Technology of Advanced Materials 15, 024603 (2014).
5. X. Chen, M. M. Milosevic, S. Stankovic, S. Reynolds, T. Dominguez-Bucio, K. Li, D. J. Thomson, F. Gardes, and G. T. Reed, “The Emergence of Silicon Photonics as a Flexible Technology Platform,” Proceedings of the IEEE
106, 2101-2116 (2018).
6. R. Halir, A. Ortega-Moñux, D. Benedikovic, G. Z. Mashanovich, J. G. Wangüemert-Pérez, J. H. Schmid, Í. Molina-Fernández, and P. Cheben, “Subwavelength-Grating Metamaterial Structures for Silicon Photonic Devices,” Proceedings of the IEEE 106, 2144-2157 (2018).
7. J. Chilles and S. Fathpour, “Silicon photonics beyond silicon-on-insulator,” Journal of Optics 19, 053001 (2017).
8. D. Marris-Morini, V. Vakarin, J. M. Ramirez, Q. Liu, A. Ballabio, J. Frigerio, M. Montesinos, C. Alonso-Ramos, X. Le Roux, S. Serna, D. Benedikovic, D. Chrastina, L. Vivien, and G. Isella, “Germanium-based integrated photonics from near- to mid-infrared applications,” Nanophotonics 7, 1781-1793 (2018).
9. Y. Li, Y. Zhang, L. Zhang, and A. W. Poon, “Silicon and optical receiver based on hybrid silicon photonic devices for intra-datacenter applications: state of the art and perspectives,” Photonics Research 3, B10-B27 (2015). 10. A. V. Krishnamoorthy and D. A. B. Miller, “Scaling optoelectronic-VLSI
circuits into the 21st century: A technology roadmap,” IEEE Journal of Selected Topics in Quantum Electronics 22, 55-76 (1996).
11. G. Roelkens, L. Liu, D. Liang, R. Jones, A. Fang, B. Koch, and J. Bowers, “III-V/silicon photonics for on-chip and intra-chip optical interconnects,” Laser & Photonics Reviews 4, 751-779 (2010).
12. O. Marshall, M. Hsu, Z. Wang, B. Kunert, C. Koos, and D. Van Thourhout, “Heterogeneous Integration on Silicon Photonics,” Proceedings of the IEEE 106, 2258-2269 (2018).
13. T. Komljenovic, D. Huang, P. Pintus, M. A. Tran, M. L. Davenport, and J. E. Bowers, “Photonic Integrated Circuits Using Heterogeneous Integration on Silicon,” Proceedings of the IEEE 106, 2246-2257 (2018).
14. S. Fama, L. Colace, G. Masini, G. Assanto, and H.-C. Luan, “High performance germanium-on-silicon detectors for optical communications,” Applied Physics Letters 81, 586-588 (2002).
15. S. J. Koester, J. D. Schaub, G. Delinger, and J. O. Chu, “Germanium-on-SOI infrared detectors for integrated photonic applications,” IEEE Journal of Selected Topic in Quantum Electronics 12, 1489-1502 (2006). 16. J. Michel, J. Liu, and L. C. Kimerling, “High-performance Ge-on-Si
photodetectors,” Nature Photonics 4, 527-534 (2010).
17. T. A. Langdo, C. W. Leitz, M. T. Currie, E. A. Fitzgerald, A. Lochtefeld, and D. A. Antoniadis, “High quality Ge on Si by epitaxial necking,” Applied Physics Letters 76, 3700-3702 (2000).
18. J. M. Baribeau, T. E. Jackman, D. C. Houghton, P. Maigné, and M. W. Denhoff, “Growth and characterization of Si1-xGex and Ge epilayers on (100) Si,” Journal of Applied Physics 63, 5738–5746 (1988).
19. H.-C. Luan, D. R. Lim, K. K. Lee, K. M. Chen, J. G. Sandland, K. Wada, and L. C. Kimerling, “High-quality Ge epilayers on Si with low threading-dislocation densities,” Applied Physics Letters 75, 2909–2911 (1999). 20. C. G. Littlejohns, M. Nedeljkovic, C. F. Mallinson, J. F. Watts, G. Z.
Mashanovich, G. T. Reed, and F. Y. Gardes, “Next generation device grade silicon-germanium on insulator,” Scientific Reports 5, 8288 (2015).
21. C. G. Littlejohns, T. Dominguez Bucio, M. Nedeljkovic, H. Wang, G. Z. Mashanovich, G. T. Reed, and F. Y. Gardes, “Towards a fully functional integrated photonic-electronic platform via a single SiGe growth step,” Scientific Reports 6, 19425 (2016).
22. J.-M. Hartmann, J.-F. Damlencourt, Y. Bogumilowicz, P. Holliger, G. Roland, and T. Billon, “Reduced pressure-chemical vapor deposition of intrinsic and doped Ge layers on Si(001) for microelectronics and optoelectronics purposes,” Journal of Crystal Growth 274, 90-99 (2005). 23. Y. H. Tan and C. S. Tan, “Growth and characterization of germanium
epitaxial film on silicon (001) using reduced pressure chemical vapor deposition,” Thin Solid Films 520, 2711-2716 (2012).
24. J. Liu, X. Sun, R. Camacho-Aguilera, L. C. Kimerling, and J. Michel, “Ge-on-Si laser operating at room temperature,” Optics Letters 35, 679-681 (2010).
25. R. E. Camacho-Aguillera, Y. Cai, N. Patel, J. T. Bessette, M. Romagnoli, L. C. Kimerling, and J. Michel, “An electrically pumped germanium laser,” Optics Express 20, 11316-11320 (2012).
26. G. T. Reed, G. Mashanovich, F. Y. Gardes, and D. J. Thomson, “Silicon optical modulators,” Nature Photonics 4, 518-526 (2010).
27. D. Marris-Morini, L. Virot, C. Baudot, J.-M. Fédéli, G. Rasigade, D. Pérez-Galacho, J.-M. Hartmann, S. Oliver, P. Brindel, P. Crozat, F. Boeuf, and L. Vivien, “A 40 Gbit/s optical link on a 300-mm silicon platform,” Optics Express 22, 6674-6679 (2014).
28. A. H. Atabaki, S. Moazeni, F. Pavanello, H. Gevorgyan, J. Notaros, L. Alloatti, M. T. Wade, C. Sun, S. A. Kruger, H. Meng, K. Al Qubaisi, I. Wang, B. Zhang, A. Khilo, C. V. Baiocco, M. A. Popović, V. M. Stojanović, and R. J. Ram, “Integrating photonics with silicon nanoelectronics for the next generation of systems on a chip,” Nature 556, 349-354 (2018). 29. L. Colace and G. Assanto, “Germanium on silicon for near-infrared light
sensing,” IEEE Photonics Journal 1, 69-79 (2009).
30. T. Yin, R. Cohen, M. M. Morse, G. Sarid, Y. Chetrit, D. Rubin, and M. J. Paniccia, “31 GHz Ge n-i-p waveguide photodetectors on Silicon-on-Insulator substrate,” Optics Express 15, 13965-13971 (2007). 31. L. Vivien, J. Osmond, J.-M. Fédéli, D. Marris-Morini, P. Crozat, J. F.
Damlencourt, E. Cassan, Y. Lecunff, and S. Laval, “42 GHz p.i.n germanium photodetector integrated in a silicon-on-insulator waveguide,” Optics Express 17, 6252-6257 (2009).
32. D. Feng, S. Liao, P. Dong, N. Feng, N. Feng, H. Liang, D. Zheng, C. Kung, J. Fong, R. Shafilha, J. Cunningham, A. Krishnamoorthy, and M. Asghari, “High-speed Ge photodetector monolithically integrated with large cross-section silicon-on-insulator waveguide,” Applied Physics Letters 95, 261105 (2009).
33. J. Joo, S. Kim, I. G. Kim, K.-S. Jang, and G. Kim, “High-sensitivity 10 Gbps Ge-on-Si photoreceiver operating at λ~1.55 µm,” Optics Express 18, 16474-16479 (2010).
34. S. Assefa, F. Xia, S. W. Bedell, Y. Zhang, T. Topuria, P. M. Rice, and Y. A. Vlasov, “CMOS-integrated high-speed MSM germanium waveguide photodetector,” Optics Express 18, 4986-4999 (2010).
35. S. Liao, N.-N. Feng, D. Feng, P. Dong, R. Shafilha, C.-C. Kung, H. Liang, W. Qian, Y. Liu, J. Fong, J. E. Cunningham, Y. Luo, and M. Asghari, “36 GHz submicron silicon waveguide germanium photodetector,” Optics Express
19, 10967-10972 (2011).
36. C. T. DeRose, D. C. Trotter, W. A. Zortman, A. L. Starbuck, M. Fisher, M. R. Watts, and P. S. Davids, “Ultra compact 45 GHz CMOS compatible Germanium waveguide photodiode with low dark current,” Optics Express 19, 24897-24904 (2011).
37. L. Vivien, A. Polzer, D. Marris-Morini, J. Osmond, J. M. Hartman, P. Crozat, E. Cassan, C. Kopp, H. Zimmermann, and J.-M. Fédéli, “Zero-bias 40 Gbit/s germanium waveguide photodetector on silicon,” Optics Express 20, 1096-1101 (2012).
38. G. Li, Y. Luo, X. Zheng, G. Masini, A. Mekis, S. Sahni, H. Thacker, J. Yao, I. Shubin, K. Raj, J. E. Cunningham, and A. V. Krishnamoorthy, “Improving CMOS-compatible Germanium photodetectors,” Optics Express 20, 26345-26350 (2012).
39. H. Pan, S. Assefa, W. M. J. Green, D. M. Kuchta, C. L. Schow, A. V. Rylyakov, B. G. Lee, C. W. Baks, S. M. Shank, and Y. A. Vlasov, “High-speed receiver based on waveguide germanium photodetector wire-bonded to 90nm SOI CMOS amplifier,” Optics Express 20, 18145-18155 (2012). 40. L. Virot, L. Vivien, J.-M. Fédéli, Y. Bogumilowitz, J.-M. Hartmann, F. Boeuf,
P. Crozat, D. Marris-Morini, and E. Cassan, “High-performance waveguide-integrated germanium PIN photodiodes for optical communication applications,” Photonics Research 1, 140-147 (2013).
41. T.-Y. Liow, N. Duan, A. E.-J. Lim, X. Tu, M. Yu, and G.Q. Lo, “Waveguide Ge/Si avalanche photodetector with a unique low-height-profile device structure,” In Optical Fiber Communications Conference, OSA Technical Digest (online), (Optical Society of America, 2014), pp. M2G.6. 42. Y. Zhang, S. Yang, Y. Yang, M. Gould, N. Ophir, A. E.-J. Lim, G.-Q. Lo, Y P.
Magill, K. Bergman, T. Baehr-Jones, Y and M. Hochberg, “A high-responsivity photodetector absent metal-germanium direct contact,” Optics Express 22, 11367-11375 (2014).
43. H. T. Chen, P. Verheyen, P. De Heyn, G. Lepage, J. De Coster, P. Absil, G. Roelkens, and J. Van Campenhout, “High-responsivity low-voltage 28-Gb/s Ge p-i-n photodetector with silicon contacts,” IEEE Journal of Lightwave Technology 33, 820-824 (2015).
44. H. Chen, P. Verheyen, P. De Heyn, G. Lepage, J. De Coster, S. Balakrishnan, P. Absil, W. Yao, L. Shen, G. Roelkens, and J. Van Campenhout, “-1 V 67 GHz bandwidth Si-contacted germanium waveguide p-i-n photodetector for optical links at 56 Gbps and beyond,” Optics Express 24, 4622-4631 (2016).
45. H. Chen, P. Verheyen, P. De Heyn, G. Lepage, J. De Coster, S. Balakrishnan, P. Absil, G. Roelkens, and J. Van Campenhout, “Dark current analysis in high-speed germanium p-i-n waveguide photodetectors,” Journal of Applied Physics 19, 213105 (2016).
46. L. Virot, D. Benedikovic, B. Szelag, C. Alonso-Ramos, B. Karakus, J.-M. Hartmann, X. Le Roux, P. Crozat, E. Cassan, D. Marris-Morini, Ch. Baudot, F. Boeuf, J.-M. Fédéli, C. Kopp, and L. Vivien, “Integrated waveguide PIN photodiodes exploiting lateral Si/Ge/Si heterojunction,” Optics Express
16, 19487-19496 (2017).
