Capacitance measurements for AlGaN/GaN photoelectrochemical electrode by using electrolyte contact and by metal contact
A semiconductor photo electrochemical electrode that contains heterostructure at the surface vicinity is attractive as a corrosion-tolerant electrode. In order to clarify its basic characteristics, the differences of Schottky junctions were evaluated using semiconductor capacitance dependent on voltage. The Mott-Schottky relationship of thin AlGaN layer on GaN was different from that of GaN bulk semiconductor. The Schottky junctions were formed not only by using metal electrode, but also by using electrolytecontact in order to evaluate the effects of the semiconductor-electrolyte interface on the behavior of Schottky junction. Although diffusions of ions and solvents exist in th electrolyte, the Mott-Schottky plot which was measured in electrolyte system showed a voltage dependence similar to that measured with metal contact. It would be probablethat an electrolyte has a limited effect on the depletion behavior of the semiconductor-heterojunction electrode: only the offset of voltage exists at the semiconductor/electrolyte interface and the offset is insensitive to the applied voltage.