Chapter 2 InAs-Alloyed GaAs Substrates for Direct Ion Implantation

Abstract

Publisher Summary Semi-insulating GaAs substrates for direct ion implantation fabrication of field effect transistors and integrated circuits have become increasingly available in the past few years. The generally preferred process for preparing semi-insulating GaAs is liquid encapsulated Czochralski (LEC) growth without the intentional addition of impurities, and many commercial suppliers are offering substrate wafers made from LEC material. The chapter discusses an approach to better uniformity based on eliminating dislocations from GaAs substrate crystals by replacing a small fraction of the Ga atoms with the isoelectronic substituent. The chapter explores the most useful technique for reducing or eliminating dislocations in GaAs while retaining the advantages of LEC growth is the substitution of In for part of the Ga. The resulting material is formally an alloy of InAs and GaAs, In x Gal 1-x As, with x usually smaller than 0.01. It seems best to designate these dilute alloys as InAs-alloyed GaAs to emphasize that the ratio of In + Ga to As is essentially unity. On the InAs-alloyed GaAs, the chapter discusses its growth, metallurgical and crystallographic behavior, electrical and optical properties, and effectiveness as a substrate for achieving uniform device properties.