MODELING OF HYDROGEN DIFFUSION IN P-TYPE GAAS-ZN

Experimental hydrogen diffusion profiles are reported in undoped and zinc doped GaAs. Hydrogen was introduced by exposure to a hydrogen plasma. The hydrogen profiles are fit using a diffusion model which assumes that hydrogen has a donor level in the band gap and diffuses as H+ and H0 in the material. It is also assumed that H+ can be trapped by ionized acceptors to form neutral complexes. Good simulations are obtained in p-type GaAs for various doping levels. We find that neutral hydrogen is present with high concentration in the diffusion process and the hydrogen molecule formation is absent. The hydrogen donor level, the diffusivities of H+ and H0, the associated activation energies and the dissociation energy of the acceptor-hydrogen pairs are determined.