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EFFECTING DOPING AND COMPOSITIONAL VARIATIONS ON MISORIENTED SUBSTRATES

IP.com Disclosure Number: IPCOM000025455D
Original Publication Date: 1985-Aug-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 104K

Publishing Venue

Xerox Disclosure Journal

Abstract

It is well known in both Si and GaAs technologies that doping concentration not only depends on many growth parameters, such as flow rates, melt composition, growth rates, growth temperatures, but also on substrate orientation. For example, Si is an amphoteric dopant in III-V materials. If Si diffuses into a Ga site, it will dope n-type and if Si diffuses into an As site, it will dope p-type. By liquid phase epitaxy, it is possible to form a p-n junction from a single Ga melt saturated with As and doped with Si. There will exist a conversion temperature for any particular set of growth conditions above which the material grows n-type and below which the material grows p-type. The conversion temperature can change drastically by just changing the orientation of the substrate from ,; 100) to either tlll)A to <111>B even though the melt conditions and cooling rates are maintained the same.

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IXEROX DISCLOSURE JOURNAL

EFFECTING DOPING AND COM- POSITIONAL VARIATIONS ON MISORIENTED SUBSTRATES Robert D. Burnham
R. Donald Yingling, Jr.

Proposed Classification
U.S. Cl. 148/171 Int. CI. C21d 1/48

It is well known in both Si and GaAs technologies that doping concentration not only depends on many growth parameters, such as flow rates, melt composition, growth rates, growth temperatures, but also on substrate orientation. For example, Si is an amphoteric dopant in III-V materials. If Si diffuses into a Ga site, it will dope n-type and if Si diffuses into an As site, it will dope p-type. By liquid phase epitaxy, it is possible to form a p-n junction from a single Ga melt saturated with As and doped with Si. There will exist a conversion temperature for any particular set of growth conditions above which the material grows n-type and below which the material grows p-type. The conversion temperature can change drastically by just changing the orientation of the substrate from ,; 100) to either tlll)A to <111>B even though the melt conditions and cooling rates are maintained the same.

By epitaxially growing layers of III-V material on a substrate with etched channels or mesas, it turns out that different crystallographic orientations are exposed depending on how the channels or mesas are oriented on the oriented substrate. We have grown double heterojunction laser structures on ,.' 100, oriented substrates using MO-CVD wherein a channel is employed in the substrate surface. The side walls of the channel form different growth regions compared to the channel bottorn and regions of the substrate surface beyond the channel. The region of growth at the bottom of the channel and the regions of growth on the substrate surface outside the channel are grown on (100) orientation whereas the growth on the channel sides are grown on (111) orientation. These different regions of orientation will provide different doping levels. For example, in a III-V regime, the doping levels of the dopants Zn and Te are different for different channel orientations. Zn and Te are not amphoteric dopants and,...