Electronic properties of a GaAs surface treated with hydrochloric acid

Processing in HCl is found to stabilize the system of surface electronic st ates of the (100) surface of n-GaAs in the temperature range 100-300 K. Dis tributions for the effective density of surface electronic states in the ba nd gap of GaAs, which are obtained from the electric-field dependence of th e surface photovoltage, depend on the measurement temperature. This is beca use the electronic states that affect the electric-field measurements are l ocated both at the boundary between GaAs and the surface film and in the fi lms themselves. Processing in HCl decreases the density of electronic state s of both types, and also decreases the concentration of deep and shallow t raps for nonequilibrium holes. These effects are even more pronounced when the processing in HCl is followed by washing in water. (C) 1999 American In stitute of Physics. [S1063-7826(99)01010-8].