Bell Telephone Laboratories

Horace C Casey, Jr

Alfred Yi Cho

Philip W Foy

Morton B Panish

Edward H Nicollian

Surface recombination current in GaAs devices is reduced by means of a semi-insulating, oxygen, iron or chromium doped monocrystalline layer of AlGaAs grown by MBE. The AlGaAs layer is grown on a GaAs body and is then masked. Diffusion of suitable impurities through a window in the mask converts the exposed portions of the AlGaAs layer to low resistivity and modifies the conductivity of the underlying zone of the GaAs body. The peripheral portions of the AlGaAs layer, however, remain semi-insulating and are effective to reduce the surface recombination velocity - diffusion length product by more than an order of magnitude.

Method of fabricating GaAs devices utilizing a semi-insulating layer of

Reduction of surface recombination current in GaAs devices

In a metal-insulator-semiconductor (MIS) structure, the I-layer comprises a single-crystal, semi-insulating layer which forms a substantially lattice-matched heterojunction with the underlying S-layer. Illustratively, the structure, grown by MBE, includes an indirect gap AlGaAs I-layer doped with a deep level impurity such as oxygen, iron or chromium, and a GaAs S-layer. GaAs FETs incorporating this MIS structure are described.

MIS Heterojunction structures

In the fabrication of double heterostructure GaAsAlGaAs junction lasers by molecular beam epitaxy, it has been found that suitably annealing the entire heterostructure increases the external quantum efficiency of the laser and reduces the room temperature threshold for lasing. Also described is a technique using relatively uncollimated beams to deposit continuously on the interior walls of the vacuum chamber fresh layers which getter deleterious contaminants. In addition, pyrolytic boron nitride, rather than graphite, effusion cells are utilized in order to reduce the amount of CO formation in the system.

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Summit, NJ, United States of America

Horace C Casey, Jr