Surface states of wet chemically etched n-Si(1 1 1):H surfaces

Impedance measurements at wet chemically etched n-Si(1 1 1):H surfaces in contact with the aqueous electrolyte 0.1 M H2SO4 reveal a surface state related capacitance extending over a potential range of 350 mV in the n-Si(1 1 1):H band gap. A detailed analysis of the impedance data allows to identify three different surface state energy levels contributing to the observed surface state capacitance. These energy levels coincide with electronic states of hydrogen interdiffused into the n-Si(1 1 1):H subsurface region, which occurs, for example, during the wet chemical preparation of n-Si(1 1 1):H surfaces. The density of the observed states in the n-Si(1 1 1):H subsurface region is of the order of (1014–1015) cm−3.