INTERFACE QUALITY AND ELECTRON-TRANSFER AT THE GAINP ON GAAS HETEROJUNCTION

Hall measurements performed on Ga0.50In0.50P/In0.20Ga0.80As structures show abnormally low mobility both at room temperature and at 77 K, an d too high electron densities which cannot be attributed to a normal t wo-dimensional electron gas in the channel. On the other hand, low tem perature photoluminescence on asymmetrical AlGaAs/GaAs/GaInP quantum w ells and x-ray photoemission spectroscopy measurements reveal the pres ence of arsenic atoms in the GaInP barrier. Using a one-dimensional Sc hrodinger-Poisson simulation with a nonabrupt interface model, we show that the presence of arsenic in GaInP leads to the formation of a par asitic GaInAsP well between the delta-doped layer and the channel, tra pping the main part of transferred electrons. We experimentally show t hat the electron transfer can be drastically improved by inserting a t hin AlInP layer at the interface. Insertion of at least six monolayers of AlInP is needed to recover a normal electron transfer as high as 2 .1 X 10(12) cm(-2). (C) 1998 American Institute of Physics. [S0021-897 9(98)02114-8]