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TIME RESOLVED STUDY OF NON RADIATIVE RECOMBINATION IN GaAs GaAlAs
HETEROSTRUCTURES
M. Pereira, B. Sermage, F. Alexandre, J. Beerens, R. Azoulay, A. Jean Louis
To cite this version:
M. Pereira, B. Sermage, F. Alexandre, J. Beerens, R. Azoulay, et al.. TIME RESOLVED STUDY
OF NON RADIATIVE RECOMBINATION IN GaAs GaAlAs HETEROSTRUCTURES. Journal de
Physique Colloques, 1987, 48 (C7), pp.C7-413-C7-415. �10.1051/jphyscol:1987799�. �jpa-00227104�
JOURNAL D E PHYSIQUE
Colloque C7, suppl6ment au n012, Tome 48, decembre 1987
TIME RESOLVED STUDY OF NON RADIATIVE RECOMBINATION IN GaAs GaAlAs HETEROSTRUCTURES
M.F. PEREIRA Jr., B. SERMAGE, F. ALEXANDRE, J. BEERENS, R. AZOULAY and A.M. JEAN LOUIS
C N E T , 1 9 6 , Avenue Henri Ravera, F - 9 2 2 2 0 Bagneux, -7rance
I
.
I r ~ t r o d u c t i o n : l ' h e 1 - h r ' c s h o l d c u r r e n t i t 1 d o u b l e h e 1 r r , o - s t r u c t u r e l a s e r s i s p r , o p o r t i o n a l t o t h e r c c o t n t ~ i n n t i orr prob:.ibi l i t v i n t h e a c t i v e l a y e r . 1 / t . . I n t h e c a s e o f t h e G a A s - G a ~ l A s l a s e r s . t h e r e c o m b i n o t i or1 p r o b a b i 1 i t y h a s two c o m p o n e n t s : t h e r - a d i a t - i v e o n e l / t r a n d t h e n o n r a d i a t i v e o n e l / t l l l . .T h e l a s e r wi 1 1 be':of p r - a c t i c a l u s e i f t i s l a r . y e cotrtpared t o t h e r . a d i a t . i v e l i f e t i m e a t t . h r . e s h o l d c a P F i e r d e n s i t y ( - 4 n s )
T h e n o n r a d i a t - . iv e r6?colnbin;~t.i011 p r o b a t j i 1 i t y . l / t ( c a l l e d S c h o k l e y - R e a d ) i s t h e sum o f t h e b u l k a n d t h e i r l \ ! & r f a c e recomt.)i n - a t i o n p r o b a b i l i t i e s :
w h e r e d i s t h e G a A s l a y e t - t h i c k n e s s a n d S = S + S i s t h e surrr o f t h e i n t e r f a c e r e c o m b i n a t i o n v e l o c i t y a t t h e two i r 1 f e r f a c : e s . E q . 2 i s v a l i d when t h e G a A S l a y e r t l ~ i c l z n ~ s s i s snral 1 cornpar-cd t o t t i c c a r r i e r d i f f u s i o r ~ le n g t h w h i c h i s t h e c a s e h e r e .
Quantunr we1 1 l a s e r s h a v e p r o v e t i t o b e i n t e r e s t i n g d e v i c e s ( 1 ) ( s m a l l e r t l l r e s h o l d c u r r - e n t , l a r g e r - r n o d u l a t i o n f r e q u e n c y ) . Howe\lt?r i n suc11 s m a l l a c t i v e l a y e r t h i c k n e s s e s t d w 5 0 - 1 0 1 ) h ) . i r r t c r f a c e r e c o m b i r l a t i or] c a n b e d r a m a t i c .
I I . E x p e r i m e n t : We h a v e s t u t l i e d F o u r s e r - i e s o f s n r n p l e s ( : 3 gr.orvrr i n M B E a n d 1 i n M O C V D ) . A l l t h e s t r u c t u r . e s c o n s i s t . e d o f a GaAs l a y e r o f t h i c k n e s s d i n c l u d e d b e t w e e n t w o G a A 1 A s l a y e r s w i t h
x a h o u t 0 . 3 . 1 X
T h e e x p e r i m e r l t n l t e c h r r i c l u ~ i s a s l'ol l o w s : we c x c i t e e;ic-h s ; i r r ~ p l e w i t h a s y n c h r o r ~ o u s l y pumped CW d y e l a s e r at: 0 . 5 8 pnt arrd o b s e r - v r t h e l u m i n e s c e n c e d e c a y wi1.h a s t r e a k camera. 'l'he G a A s 1 um 1 n c s - c e n c e i s s e l e c t e d w i t h a 111onoctrr.otr1ator a n d t h e t.elnpor-a l r e s o l u - t i o n o f t h e s y s t e m i s a b o u t . 1 0 p s . E x a m p l e s o f I~lmiriescerrc:e cle- c a y c u r . d e s o b t a i n e d w i t h t h e s t r e a k c a m e r a a t . low e x c i t a t i o n a r . e g i v e n i n f i g . 1 .
T h e c a r r i e r s 1 i f e t i m e ( t ) arrd t h e lurrlinesr:errce 1 i f r t i t n e ( t ) at- t h e e n d o f t h e e x c i t a t i o n p u l s e a r e r e l a t e d t)y : L
t = t d L o y ( I L ( 0 ) ) / d L o g ( n ) = t.L d L o ~ ( I L ( 0 ) ) / d L o q ( P e x )
L ( 3 )
w h e r e I ( 0 ) i s t h e Irrrni rlescc2rrcc i r r t e r r s i t y a t t h a l t irt~f,.
L
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1987799
JOURNAL DE PHYSIQUE
Ftq. 1 : Examples o f luminescence decay F i a . 2 : Y a r l a t t o n w i t h e x c i t a t l o n o f curves obtatned w l t h the streak camera the t o t a l
( + I
r a d f a t t v e ( A ) and non a tlow
e x c i t a t i o n . r a d t a t f v e (01 recombtnatton probabt 1 t ty.T h e r a d i a t i v e l i f e t i m e t i s o b t . a i n e d f r o m :
r
F o r e a c h s a m p l e , w e p l o t t h e r e c o n ~ b i r l a t i o n p r o b a b i l i t y l / t arid I / P e x a s a f u n c t i o n o f l J e x a s s h o w n i n F i q . 2
.
A t l o w e x c i t a t i o n14t
i s r ~ e a r l y c o n s t a n t w h i l e l / t d e c r e a s e s , s h o w i r l y t h a t . t h i s c o n s t a n t v a l u e i s t h e p r o b a b i 1 i t C o f 11or1 r . a d i a t . i v e r e c o m b i n a t i o n l / t.
F i g . 3 d i s p l a y s t h e r a d i a t i v e a n d t h e t - o t a l r e c o m b i n a t i o n p r o 6 5 b i 1 i t y f o r d i f f e r e r i t . G a A s t h i c k n e s s e s .F t a .
3
: Y a r l a t t o n w i t h e x c i t a t l o n o f 4 : Y a r t a t l o n o f the non r a d l a - the t o t a l(-1
and r a d t a t t v e (A) recom-?'-
t ve recombtnatton probabt 11 t y wl t h b t n a t t o n probabtl t t y f o r d l f f e r e n t the Inverse GaAs l a y e r thtcknessesGaAs thtcknesses. f o r the three sertes.
F o r l a r g e GaAs t . l i i c l ~ n e s s e s ( d > 2 0 0 A ) I/t.,, f o l l o w s e q . 2 as stlowll i n F i g . 4 .
F o r s m a l l GaAs t h i c k n e s s e s ( d < 2 0 0 a ) , S ( g i v e n b y S = l / t n r f .
x d ) i n c r e a s e s a s f o r e s e e n b y DUggEin e t . a l . ( l ) d u e t o F i e l n c r e a s e o f t h e l e a k i n g o f t h e c a r r i e r s w a v e f u n c t i o r l s iri t,tie G a A l A s c o n - f i n e m e n t l a y e r s .
F i g . 5 : S as a function o f well width (+) F i g . 6 : S as a function of T i i T ' f T M B E series, ( A ) second MBE series, T F l l T i d t h ( 0 ) experimental
( A ) MOCVD series. Calculated models f o r p o i n t s s o l i d l i n e : c a l c u l a t e d b a r r i e r
(-1
and i n t e r f a c e(---I
recombi- model w i t h b a r r i e r+
well im-n a t i o n . p u r i t y p r o f i l e recombination.
Fig.5 shows experimental values of S for small values of d a s well a s two theoretical curves assuming : 1)uniform distribution of nonradiative recornbinatiorls centers in the GaAlAs barriers; 2 )
recombinating centers concentrated at. t,he interfaces.
The curves are calculated for an offset of the coriduction band equal to 67% of the band gap(?)
Fig.6 shows S measured for a series o f polluted samples. A calcu- lation that extends the previously cited models by adding to the recombinat-ion at the barriers the contribution of a n impurity profile that decays exponeritially from the interface towards the GaAs layer is also shown.
T h e increase of the interface recornbination velocity represented in Fig.5 is importarit for ( U . W . ) lasers. For exalllple in the case o f the secorlci MBE series, the non radiative lifetime Tor 0 . 1 Pln
thick layers is 100 n s which is negligible compared to the radi- ative lifetime in usual DH lasers which is about 4 ns. However in the case of a quantum well of 50A, t h e non radiative lifetime is about 2 s arid increases the calculated threshold current from
1 1 0 A/cm9 in SCH optimised ( Q . W . ) lasers.
REFERENCES
( 1 ) G.Duggan, tI.J.Ralptl and R.J.Elliot, Solid State Comm. 56, 17
( 1985)
( 2 ) G.Danan, B.Etienne. I;.Mollot, R.Plarie1, A.M.Jean-l_or~is, F.
Alexandre, B.Jusserand. G . L e Roux, J.Y.Marzin, H.Savary and B.Sermage, Phys.Rev. B, 35. 6207 ( 1 9 8 7 )
