DRY SEQUENTIAL PROCESS OF PHOTOCHEMICAL ETCHING AND SURFACE PASSIVATION OF IN0.52AL0.48AS USING HBR AND H2S

In order to improve the Schottky diode characteristics of metal-In0.52 Al0.48As, a new dry photochemical etching and sulfur passivation proce ss has been developed. Excimer and deep UV lamps were used for photoch emical etching and surface passivation, respectively. Auger electron s pectroscopy measurement shows that this passivation process is as good as wet (NH4)(2)S-x and P2S5/(NH4)(2)S passivation in terms of sulfur coverage. Schottky diodes were fabricated on n-In0.52Al0.48As by elect ron beam evaporation of a multilayer metal contact of the form Mo/Ti/P t/Au (2/30/300/200 nm). The leakage current has been reduced by three orders of magnitude after applying this passivation process. X-ray pho toelectron spectroscopy measurements illustrate that these free S rad icals are capable of replacing As-O and In-O bonds to As-S and In-S bo nds. The conclusion is that the As-O and In-O bonds are the primary ca uses of leakage current. These bonds are dissolved after this photoche mical sulfur surface passivation. (C) 1995 American Vacuum Society.