OXIDATION PROCESSES IN UNDOPED GAAS AND IN SI-DOPED GAAS

Samples of undoped GaAs- and Si-doped GaAs were oxidized at different oxidation temperatures, for different durations. Three different exper imental techniques that complete each other were used: Raman scatterin g, Auger electron spectroscopy, and the ellipsometry technique. The gr owth of crystalline arsenic layer takes place after oxidation during 1 0 h, 45 min, and 5 min at temperatures of 400, 500, and 600-degrees-C, respectively. The oxide layer is formed as a result of three competin g processes: diffusion in accordance with Fick's law, diffusion with l arger diffusion coefficient through the oxide layer, and stopping of d iffusion by the crystalline arsenic layer that grows at the GaAs/oxide interface. The effect of Si doping on the oxidation process of GaAs i s to impede the crystallization of the arsenic layer, to diminish the diffusion coefficient in the course of the initial stages of the react ion between the oxygen and GaAs, and to cause a small rise in the acti vation energy.