Shallow and selective diffusion of zinc in indium phosphide

Diffusion experiments at 670–720°C from doped silica films into n-type InP are described. The diffusant is Zn. The films are spun on from emulsions and carefully solidified. The diffused samples were investigated mostly by stain etching and additionally by C-V and break-down measurements on Schottky diodes, by four-point-probe and Hall measurements. Homogeneous diffusion fronts were obtained. From the square-root dependence of the diffusion depth on the diffusion time and from the measurements mentioned before an errorfunction-complement type of diffusion profile can be inferred. The evaluation of the results then gives a diffusion coefficient of (2 ± 1) × 10^?10 cm²/s and a total Zn concentration at the surface of about 2 × 10¹⁸ cm^?3. It is demonstrated that with conventional photolithography selective diffusions can be performed.