Electrical properties of electrolyte-GaN junction during photoelectrical etching processing

Recently porous semiconductors have stimulated much of interests, because they exhibit different physical properties relative to those of bulk crystals. The high surface area, band gap shift, and efficient luminescence promised the use of porous semiconductor over a wide range, from optoelectronics to chemical and biochemical sensors applications. One of the most common techniques to fabricate porous GaN is the photo-assisted electrochemical etching. The main factor in the photo-assisted electrochemical etching is the electrolyte. When immersed in an electrolyte, the semiconductor exchanges electrons with the electrolyte along the surface because the Fermi level in the semiconductor is different from that of the electrolyte. As in the semiconductor-metal contacts, an energy barrier is formed, the effective height of which is often fixed by the distribution of surface states in the semiconductor. This paper investigates the use of four different electrolytes to study the electrical properties of the electrolyte-GaN contacts in the photoelectrochemical etching processes. Thermionic emission theory is used to investigate the mechanism of the current transport through metal-semiconductor interfaces. From I-V characterization, the Schottky barrier height, ideality factor, and series resistance are calculated.