Electrodeposition of GaAs from Aqueous Electrolytes

Abstract

Gallium arsenide films were electrodeposited from both alkaline and acid aqueous electrolytes. Compared to other conventional methods of preparing gallium arsenide films, electrodeposition from aqueous solution has the advantages of low operating and equipment costs, relatively easy control of film properties, and no toxic volatile raw material. The cathodic deposits from an alkaline electrolyte generally were thick, porous, and powdery. With an acid electrolyte, the deposits were thinner and more compact and adherent. The effects of the following operating parameters have been characterized: applied potential, current density, electrolyte composition, cathode material, deposition temperature, pH, additives, and agitation. Secondary ion mass spectroscopy confirmed oxidation states and x‐ray diffraction patterns indicated that the as‐deposited films were microcrystalline which became more crystalline on annealing. Mixtures of the deposited elements of gallium and arsenic yielded crystalline gallium arsenide after annealing. Energy dispersive spectroscopy and Auger electron spectroscopy showed that the deposited films contained some oxygen. The source of the oxygen, particularly in the acid electrolytes, is discussed. A mechanistic study confirmed conditions under which arsine is formed and reacts with gallate in the alkaline solution.