Chalcogen based treatment of InAs with [(NH4)2S/(NH4)2SO4]

A sulphur based chemical, ([(NH4)2S/(NH4)2SO4]) to which S has been added not previously reported for the treatment of (111)A InAs surfaces is introduced and benchmarked against the commonly used passivants Na2S·9H2O and ((NH4)2S + S), using Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). It has been found that the native oxide layer present on the InAs surface is more effectively removed when treated with ([(NH4)2S/(NH4)2SO4] + S) than with ((NH4)2S + S) or Na2S·9H2O. AES depth profiles of the sulphurized layers revealed the formation of a thin (less than 8.5 nm) In–S surface layer for both ((NH4)2SO4 + S) and ([(NH4)2S/(NH4)2SO4] + S) treatments. No evidence for the formation of As―S bonds was found. Treatment with ([(NH4)2S/(NH4)2SO4] + S) also affected a significant improvement compared to the more established sulphur treatments in the surface morphology of the otherwise poor as-received n-InAs (111)A surface.