Magnetic properties of amorphous Fe‐Er‐B‐Si ribbons

Magnetic properties of amorphous FeErBSi ribbons

R. Krishnan, H. Lassri, and P. Rougier

Citation: Journal of Applied Physics 62, 3463 (1987); doi: 10.1063/1.339288 View online: http://dx.doi.org/10.1063/1.339288

View Table of Contents: http://scitation.aip.org/content/aip/journal/jap/62/8?ver=pdfcov Published by the AIP Publishing

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negligible undercutting and excellent "adhesion." The lower InGaAsP layer also serves as a perfect etch-stop layer, so the etch depth is well controlled. In addition, for mask edges running parallel to the [011] direction, HCl reaches a crys- tallographic etch-stop plane a few degrees past the (01

I)

face. This leads to a near-rectangular profile as idealized in Fig. 1 (c).

Figures 2 and 3 show the results obtained for the two different pitches. In the "second-order" case, the grating is very precisely controlled both in depth and profile, forming a nearly perfect square wave. Of course this is merely to dem- onstrate the principle since a square wave has only odd Four- ier components and cannot function in second-order DFB or DBR applications. In the first-order case, the grating

"teeth" are only - 1100

A

A

Deep grooves with high aspect ratios and very high spa- tial resolution have also been possible in recent years using electron beam lithography combined with dry etching tech- niques.⁹ However, electron beam lithography over extended areas suffers from long writing times and small writing win- dows without "stitching." In addition, crystal damage can potentially occur during the dry etching process itself. The gratings shown in Figs. 2 and 3 are done entirely by wet etching and should thus be free of damage, and the areas are limited only by the holographic exposure size, which is on the order of 1 in. in our apparatus.

One limitation of the specific technique illustrated in Fig. 1 is that it requires grating lines along the [011] direc- tion, or optical propagation along the [01

I]

lar laser structures. Another requirement is that the grating be in InP. This does not impose serious limitations, since gratings below the InGaAsP guide or active layer are usually initiated with corrugations in InP followed by a quaternary growth. For gratings above the active layer, the InP corruga- tion can be followed by another quaternary growth before a final InP growth to provide the required index difference. In addition, both the orientation and material requirements are peculiar to the example shown, and other material/selective etch combinations may be possible using similar principles.

In closing, we have demonstrated a method for fabricat- ing unusually deep, narrow-pitch gratings with highly regu- lar and reproducible depths and profiles. This should prove useful where strong or larger mode volume gratings are re- quired. We also believe that applications of this type for ul- trathin etch-stop layers and selective etchants, combined with the new generation of computer controlled growth faci- lities such as CBE, will play an increasing role in device fabrication.

IT. E. Bell, IEEE Spectrum 20, 38 (1983).

2R. C. Alferness, C. H. Joyner, M. D. Divino, M. J. R. Mart yak, and L. L.

Buhl, App!. Phys. Lett. 49,125 (1986).

3T. L. Koch, E. G. Burkhardt, F. G. Storz, T. J. Bridges, and T. Sizer, IEEE J. Quantum Electron. QE-23, 889 (1987).

'W. T. Tsang, App!. Phys. Lett. 45,1234 (1984).

ST. L. Koch, W. T. Tsang, and P. J. Corvini, App!. Phys. Lett. 50, 307 (1987).

6L. D. Westbrook, A. W. Nelson, and P. J. Fiddyment, Electron. Lett. 19, 1076 (1983).

7p. J. Corvini, L. Eichner, and A. B. Piccirilli (unpublished).

8L. A. Coldren, K. Furuya, B. I. Miller, and J. A. Rentschler, IEEE J.

Quantum Electron. QE-18, 1679 (1982).

9See, for example, E. L. Hu and R. E. Howard, App!. Phys. Lett. 37, 1022 (1980); also E. L. Hu, R. E. Howard, P. Grabbe, and D. M. Tennant, J.

Electrochem. Soc. 130,1171 (1983).

MagnetiC properties of amorphous Fe-Er-8-Si ribbons

R. Krishnan, H. Lassri, and P. Rougier

Laboratoire de Magnetisme, 92195 Meudon Principal Cedex, France

(Received 30 March 1987; accepted for publication 22 June 1987)

We report on our magnetic studies of amorphous (Fe_{1 _",} Er", )soB₁₂Sis ribbons with

o <x < 0.125 prepared by melt spinning. With the addition ofEr, both magnetization and Tc decrease. For instance, for x = 0.125, the magnetization has fallen from the initial value of 175 to 108 emu g-l and Tc from 660 to 500 K. In-plane hysteresis loops show practically zero remanence and low coercivity of 1.0 Oe.

Studies on magnetic glasses based on 3d transition met- als are abundant and well documented in the literature.

However, there are very few studies on corresponding ones based on rare-earth metals. Cornelison and Sellmayer have

reported on the magnetic properties ofrare-earth gallium-

iron glasses (rich in rare earth) prepared by splat cooling techniques. ¹ Contrary to 3d metals, rare-earth metals pos-

sess large spin-orbit interaction (except Gd), and hence their presence could give rise to large random anisotropy. ² We have undertaken a study of amorphous TM-R-B-Si rib- bons, where TM = Fe and Co, and R stands for the rare-

earth metal, in order to study the evolution of spin structure,

the magnetic moment, and eventually the anisotropy. In this note we present our preliminary results on the magnetic

3463 J. Appl. Phys. 62 (8), 15 October 1987 0021-8979/87/203463-02$02.40 @ 1987 American Institute of Physics 3463 [This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP:

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~.---~---~

700 600 500

400

o 0·05 0.10

x-

FlO. 1. Magnetization and Curie temperature variation with Er concentra- tion.

properties at 290 K of amorphous (Fe_{l ....:}x Erx )soBl2Sig

with x = 0, 0.03, 0.05, and 0.125.

The ingots were first prepared from metals with purity better than 99.9%. Amorphous ribbons were then prepared by melt spinning with the use of a single-roller technique with tangential velocity in the range 30-40 m s - I. The amor- phous structure was verified by x-ray diffraction.

Magnetization and hysteresis loops were studied with a vibration sample magnetometer with applied fields up to 17 kOe. Curie temperature was determined in an applied field of about 100 Oe.

With H applied in the ribbon plane, technical saturation could be obtained for H;::: 1 kOe. Figure 1 shows the vari- ation of the alloy magnetic moment ^(0" in emu g-I) and Curie temperature (T c ) with Er content. There is an almost

linear decrease in ^0" for 0 < x < 0.05. Then for x> 0.05, 0"

decreases more slowly. The variation of the Curie tempera- ture T c with x is also somewhat similar to that of the mag- netic moment. The decrease in 0" could be caused by at least two factors. The first arises from the antiferromagnetic cou- pling between Fe and Er moments, leading to a decrease in 0".

The second is due to the close proximity of T c to the ambient temperature where the measurements have been made.

In-plane hysteresis loops were studied with the field ap- plied both along the length and width of the ribbon samples.

The effect of Er on the nature ofthe loops was not remark- able. For all the samples, the easy axis was along the ribbon length. The in-plane uniaxial anisotropy field is 150 Oe for x

=

In summary, we prepared amorphous Fe-Er-B-Si rib- bons and shown that both 0" and Tc decrease with Er substi- tution. The hard axis in-plane hysteresis loops indicate prac- tically zero remanence and very low coercivity in the as-quenched state.

Detailed studies of magnetization at high fields and low- er temperatures will be reported in the near future.

IS. o. Cornelison and D. J. Sellmyer, Phys. Rev. B 30,2845 (1984).

2R. w. Cochrane, R. Harris, and M. J. Zuckermann, Phys. Rev. 48, 1 (1978).

30. P. Meisner, Appl. Phys. Lett. 50, 116 (1987).

Radiation defect distribution in proton-irradiated silicon

W. Wondrak

AEG Research Institute. 6000 Frankfurt 71, Federal Republic of Germany K. Bethge

Institutfur Kernphysik, Universitiit Frankfurt, 6000 Frankfurt. Federal Republic afGermany D. Silber

Fachbereich 1. Universitiit Bremen. 2000 Bremen. Federal Republic of Germany

(Received 26 February 1987; accepted for publication 12 June 1987)

Defect concentration profiles covering a range of -100 J-lm in high-energy proton-irradiated silicon (3 MeV) have been investigated using deep-level transient spectroscopy. Radiation damage is produced in a layer between the surface and the proton end of range. The maximum defect concentrations are found at about the projected proton range. In this region, the relative concentration of centers with favorable energy levels for power device applications is

remarkably large.

Investigations on defect concentration profiles in silicon obtained from high-energy proton irradiations were stimu- lated from new requirements for carrier lifetime control in silicon power-device technology in order to achieve opti- mized switching behavior. ¹ In contrast to the well-known gold diffusion and high-energy electron-irradiation technol-

. ogies, ^2.3 proton irradiation produces narrow "recombina- tion layers." These should enable tailoring of optimized re- combination center distributions. ^4-6

3464 J. Appl. Phys. 62 (8). 15 October 1987

For these applications, it is desirable to know the con- centration profiles, the relative abundances, and the elec- tronic properties of the different radiation defects.

0021-8979/87/203464-03$02.40 © 1 987 American Institute of PhysiCS 3464 [This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP:

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