Effect of crystal orientation and doping on the activation energy for GaAs oxide growth by liquid phase method

We have investigated the oxide growth kinetics of near-room-temperature liquid phase chemical enhanced oxidation on differently oriented and doped GaAs substrates. Oxidation reactions have been studied by analyzing their activation energies and have been found to depend on the bond configuration of crystal planes. Experimental results indicate that the activation energies are independent of the doping of GaAs. The oxidation rates are dopant selective (n^- :p⁺-GaAs∼4:1 at 30°C under illumination) and sensitive to illumination (without:with illumination∼1:25 at 30°C for a n⁺ -doped GaAs). In the oxidation reactions, photogenerated holes are found to play an important role. Finally, we have proposed a mechanism based on the band bending and the carrier transport near the oxide-GaAs interface to interpret the experimental observations.