A comparative study of Si doping in GaAs layers grown by molecular beam epitaxy on GaAs(110) and GaAs(001) surfaces

A comparison of Si doping behavior in GaAs layers on (110) and (001) surfaces under the same growth conditions shows that the autocompensation ratio in (110) layers is usually higher than in (001) layers. However, under certain conditions (low substrate temperature, high As-4 pressure, and low Si flux), the free electron concentration in the (110) layers can actually be higher. We attribute this behavior to Ga vacancy traps in the (001) surface layers; whereas layers on the (110) surface remain almost defect free. Our results help to clarify the mechanism of defect generation in the (001) layers, which leads to reduced carrier concentration at low growth temperatures. (C) 1997 American Institute of Physics.