Photoelectrochemical Studies and Capacitance Measurements during the Nitride Passivation of InP in Liquid Ammonia (-55°C)

Abstract

This paper is based on fundamental photo-electrochemical studies of an anodic passivation process at the interface n-InP/liquid ammonia (-55 °C). Thanks to X-ray Photoelectron Spectroscopy analyses, a reproducible polyphosphazene like film was reported on InP (-[(H2N)-P=N]n-). A variation of the interfacial potential close to one volt is observed during the galvanostatic treatment. According to the anodic charge a gradual shift of the flat band potential is revealed while keeping the same slope of the Mott-Shottky straight line. As a consequence the graphical representation of C-2 = f(V) becomes drastically flat and extended over 1 volt. The modification of InP surface leads then to a high interfacial capacitance (≈ 2µF.cm-2). The almost total lack of the photo-potential is another significant consequence of the passivation of InP. These results suggest the accumulation configuration of the modified interface.