Sulfur incorporation in VPE GaAs

Abstract

An experimental study of the epitaxial growth of sulfur doped GaAs films from the HCl-Ga-AsH 3-H 2 system shows proportionality between pH 2S in the gas phase and the electron concentration ( n) in the layers on (100) and (111) As samples. Only on (111) Ga samples a limited range with p 1 2 H 2S dependence is observed. The distribution coefficient of sulfur depends strongly on substrate orientation and process parameters. SIMS data indicate that the incorporation of sulfur continues according to a linear rate law, after the saturation value for n of approximately 3×10 18 cm -3 has been reached. Samples obtained for H 2S pressures larger than those required for this saturation value have reduced mobilities. Our findings indicate that the sulfur uptake is kinetically determined in most cases.