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

We have investigated the oxide growth kinetics of near-room-temperature liq uid phase chemical enhanced oxidation on differently oriented and doped GaA s substrates. Oxidation reactions have been studied by analyzing their acti vation 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 selec tive (n(-):p(+)-GaAs similar to 4:1 at 30 degrees C under illumination) and sensitive to illumination (without:with illumination similar to 1:25 at 30 degrees C for a n(+)-doped GaAs). In the oxidation reactions, photogenerat ed holes are found to play an important role. Finally, we have proposed a m echanism based on the band bending and the carrier transport near the oxide -GaAs interface to interpret the experimental observations. (C) 2000 Americ an Institute of Physics. [S0021-8979(00)04002-0].