The influence of n-type Si and p-type Zn dopants on the low-temperature thermal oxidation of GaAs was studied by Raman scattering and Auger electron spectroscopy. It was found that the oxidation process is significantly affected by the dopants, resulting in a much thinner oxide layer than that obtained in undoped GaAs. The arsenic liberated by the oxidation reaction was observed to accumulate at the oxide/GaAs interface. The process of free As buildup at the interface is accompanied by its crystallization and both processes are strongly enhanced by the presence of dopants.