Galvanic corrosion behavior of GaAs in acid solutions

The galvanic corrosion behavior of both n-GaAs and p-GaAs coupled to Au, at room temperature, have been examined using the zero resistance ammeter technique (direct measurement), as well as the method of superposition of polarization curves (indirect measurement). Galvanic current densities, which can be converted to corrosion rates, were measured as a function of the cathode-to-anode (C /A) area ratio. In addition, corrosion rates were predicted from superposition of cathodic polarization curves for Au and anodic polarization curves for GaAs. With some exceptions, the current densities increased with increasing C/A ratio, and the agreement between the indirect and direct measurements was quite good. This indicates that the former can be used to determine semiconductor corrosion rates. Sample surfaces, examined using transmission electron microscopy, showed an As-rich surface layer, with a thickness dependent on dopant type and polarization potential.