Photo-Electrochemical Etching of III-V Semiconductors

A convenient means for controlling III-V wet chemical etching processes is to use light to generate minority carriers at the semiconductor surface where they can serve as oxidizing or reducing agents, depending on the carrier type, to drive electrochemical reactions. For example, projection or holographic imaging techniques can be employed to create arbitrary profiles in the semiconductor surface. Since nearly all photons with energies above the bandgap can be used efficiently, etching rates of several um/min are obtainable with incandescent sources. With an appropriate choice of electrolyte and biasing conditions, the resultant etched surface can be made specular. In addition, the process can be made selective for materials variations including doping type, composition, and crystal quality.