Chemical passivation of gallium arsenide surfaces and devices
Abstract
Recent inorganic sulfide treatments have been shown to be effective in reducing the surface recombination velocity and surface state density of GaAs surfaces for limited periods of time. These treatments result in a reduction the edge currents of GaAs PN homojunction diodes. With this success, an investigation of the passivation mechanism has been conducted. XPS was used to investigate the chemical passivation mechanism. The (NH$\sb4)\sb2$S treated surface was found to be free of any oxide and covered with a near monolayer of sulfur. The near monolayer of sulfur was found to dramatically reduce the initial oxidation rate. However, the (NH$\sb4)\sb2$S treated surface eventually oxidized similar to an acid etched sample. Schottky barrier diodes were fabricated on (NH$\sb4)\sb2$S treated GaAs samples. The Schottky barrier heights exhibited an increased dependence on metal work function. However, the ideal Schottky barrier height limit was not obtained. MBE regrowth on the ammonium sulfide treated GaAs (100) surface exhibited a physically invisible interfaces when probed by TEM and had an excellent interface electrically. A permanent As$\sb2$S$\sb3$ treatment has been shown to be effective in reducing perimeter current associated with exposed surfaces for forward bias diodes, HBTs, and reverse biased PiNiP dynamic memory capacitors.
Degree
Ph.D.
Advisors
Melloch, Purdue University.
Subject Area
Electrical engineering
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