Formation of p+(p-)n junctions in InP and their dependence on substrate concentration, time and temperature

To investigate the diffusion mechanism in InP, Zn was diffused from a solid source of Zn3P2, which has been evaporated onto the surface of the samples and covered by an Al2O3 layer to prevent thermal degradation. This simple technique provides a degradation-free and reproducible diffusion process. The formation of p+p-n- and p+n(+) junctions and their dependence on substrate doping (3*1015 cm-3 to 1018 cm-3), time and temperature are studied. It is shown that for low-doped InP, the position of the p+p- and p-n junctions can be controlled independently by choosing an appropriate combination of time and temperature. Furthermore simple empirical equations are obtained for the activation energy and the pre-exponential factor of the diffusion constant as a function of the substrate doping concentration.