Planar Zn diffusion in InP

A procedure for achieving well-behaved planar Zn diffusion to a controllable depth in n-type InP is described. The dilute-Zn diffusion, which utilizes a Zn+Ga+P source (in an evacuated ampoule), is performed in the temperature range 650–700°C. The low diffusion temperatures employed assure that any previous junctions that might be prepared, such as LPE heterojunctions, are not affected by the diffusion process. The masking afforded by Si₃N₄ and partial “masking,” or attenuation, afforded by SiO₂ on InP are demonstrated. The results obtained suggest that dilute-Zn diffusion in InP, with a significant P over-pressure, favors a substitutional diffusion mechanism that probably follows a complementary error function distribution.