Abstract
To evaluate polishing and cleaning methods for gallium arsenide, the surface film thickness is estimated by ellipsometry. For measurements made at a wavelength of 5461Aå, a refractive index of 1.9 is assumed for the film, and an extinction coefficient of 0.304 is assumed for the gallium arsenide. The film thickness is found to be correlated with the cleaning method and a simple and effective cleaning procedure is proposed. The refractive index and the extinction coefficient measured at wavelengths of 4375 and 5461Aå for gallium arsenide samples prepared by three commonly used polishing techniques are the same as those of freshly grown epitaxial gallium arsenide. For clean samples the thickness of the surface film increases when the gallium arsenide is exposed to air until a final thickness of about 30Aå is reached after a few days. Experimental data describing the behavior of Schottky diodes on differently prepared surfaces are presented. The barrier height increases by 0.07 eV when the thickness of the film increases from 8.5 to 16Aå. The reverse bias current‐ voltage characteristics are explained by existing interfacial layer theories. The annealing of aluminum oxide films on gallium arsenide is also reported.