Wavelength dependence of optically induced oxidation of GaAs(100)

The wavelength dependence of optically induced, room-temperature oxidation of GaAs (100) is reported. The sample illumination was performed with either continuous wave (cw) or pulsed-laser sources radiating at different wavelengths, in the range of 248–514 nm. The thickness of optically induced oxides, ranging from 1 to >50 Å, was measured with x-ray photoelectron spectroscopy. It was found that the oxidation is always much more rapid in deep-ultraviolet than in near-ultraviolet or visible wavelength regions. This effect is attributed to the generation of hot carriers at the semiconductor surface under ultraviolet light.