Comparison of Semiconductor–Electrolyte and Semiconductor–Metal Schottky Junctions Using AlGaN/GaN Photoelectrochemical Electrode

Abstract

A semiconductor photoelectrochemical electrode that contains a heterostructure at the surface vicinity is attractive as a corrosion-tolerant electrode. In order to clarify its basic characteristics, the differences in Schottky junctions were evaluated using the semiconductor capacitance dependence on voltage. The Mott–Schottky relationship of a thin AlGaN layer on GaN was different from that of GaN bulk. The Schottky junctions were formed not only by using an electrolyte contact, but also by using a metal electrode to evaluate the effects of the semiconductor–electrolyte interface. Although diffusions of ions and solvents occur in the electrolyte, the Mott–Schottky plot measured for the electrolyte system showed a similar voltage dependence slope to that measured with a metal contact. This indicates that an electrolyte has a limited effect on the depletion behavior of the semiconductor heterojunction electrode.