Reduced interface state density after photocurrent oscillations and electrochemical hydrogenation of <i>n</i>-Si(111): A surface photovoltage investigation

Abstract

The electrochemical H-termination process of n-Si(111) surfaces in aqueous 0.1 M NH4F pH 4.0 solution was optimized for a two step procedure consisting of the surface smoothing during oxidation in the photocurrent oscillating potential region followed by the oxide etching and passivation of the surface atoms with hydrogen. The hydrogen termination was monitored in situ measuring the dark current transient and evaluated using pulsed surface photovoltage technique. An unusually low density of interface states it=1×1010 eV−1 cm−2 was obtained by the hydrogen termination on n-Si(111) surfaces following this procedure with better results than applying an electropolishing treatment.