Chemical and electronic properties of sulfur-passivated InAs surfaces

Treatment with ammonium sulfide [(NH4)2Sx] solutions is used to produce model passivated InAs (001) surfaces with well-defined chemical and electronic properties. The passivation effectively removes oxides and contaminants with minimal surface etching, and creates a covalently bonded sulfur layer with good short-term stability in ambient air and a variety of aqueous solutions, as characterized by x-ray photoelectron spectroscopy (XPS), atomic force microscopy, and Hall measurements. The sulfur passivation also preserves the surface charge accumulation layer, increasing the associated downward band bending