Self‐aligned Si‐Zn diffusion into GaAs and AlGaAs

A practical technology for self‐aligned Si‐Zn diffusion into GaAs and AlGaAs has been developed. It is found that the use of a Si film alone for self‐aligned Si‐Zn diffusion is subject to serious problems of morphology degradation and doping contamination during the process of the Si diffusion. A procedure combining the use of a SiO2 film as an encapsulant with a sputtered Si film as source for Si diffusion and mask for Zn diffusion is investigated in detail. Optimum thicknesses of the Si and SiO2 films are determined to be 180 and 550 A, respectively.