Wet-chemical etching of III-V semiconductors

Ill-V semiconductors like GaAs can be wet-chemically etched by three mechanisms: electrochemically with an external voltage source, electrochemically using an oxidizing agent (elec troless), and chemically with a reactive compound. In some cases the etching process only proceeds when the semiconductor is exposed to light. The etch rate depends on the relative reaction rate at the semiconductor surface and the mass transfer in the solution. Other important factors are the effect of the crystal planes, the orientation of a mask with respect to these planes, and the electrical contact with other materials. Wet-chemical etching of Ill-V semi conductors can be used on a large scale for various applications, including the detection of crystallographic defects, the fabrication of special profiles and the selective dissolution of closely related materials in multilayer structures.