The structural dependence of light sensitivity in (Al,Ga)As/GaAs modulation doped heterostructures

Understanding the origin and nature of light sensitivity in (Al,Ga)As/GaAs modulation doped heterostructures is becoming important as modulation doped field effect transistors move from the research laboratories into practical application. Control of threshold voltage in an integrated circuit is crucial. If these devices are to be operated at cryogenic temperatures to take advantage of their enhanced transport properties then the persistent photoconductive effects associated with these structures cannot be ignored. This paper examines the dependence of light sensitivity on the thicknesses of the doped (Al, Ga)As layer and the undoped GaAs buffer layer. The use of As2 as opposed to As4 is investigated. Based upon these results, the origin and behavior of the persistent photoconductivity is reexamined. © 1984 AIME.