Electronic properties of a GaAs surface treated with hydrochloric acid

Processing in HCl is found to stabilize the system of surface electronic states of the (100) surface of n-GaAs in the temperature range 100-300 K. Distributions for the effective density of surface electronic states in the band gap of GaAs, which are obtained from the electric-field dependence of the surface photovoltage, depend on the measurement temperature. This is because the electronic states that affect the electric-field measurements are located both at the boundary between GaAs and the surface film and in the films themselves. Processing in HCl decreases the density of electronic states of both types, and also decreases the concentration of deep and shallow traps for nonequilibrium holes. These effects are even more pronounced when the processing in HCl is followed by washing in water. (C) 1999 American Institute of Physics. [S1063-7826(99)01010-8].