We study the effect of hydrogen passivation on Al1-xGal-xAs grown by liquid
-phase epitaxy (LPE) on semi-insulating GaAs. Using surface photovoltage (S
PV) spectroscopy and Hall measurements we investigate the effect of hydroge
nation on AlxGa1-xAs epilayers with electron concentrations in the range 10
(16)-10(17)cm(-3). We measure the minority carrier diffusion length in the
as-grown AlxGa1-xAs epilayers to be in the range 0.1-0.8 mu m and to increa
se significantly upon hydrogenation. Hydrogen passivation of interface stat
es at the heterojunction is demonstrated for epilayers with low carrier con
centration. We apply the result from the SPV measurements to speculate on t
he band bending at the heterojunction. (C) 1999 Elsevier Science B.V. All r
ights reserved.