Observation of pn-junction depth in Mg2Si photodiode fabricated by thermal diffusion of Ag acceptor

We have investigated the relationship between the Ag concentration and the pn-junction depth in the Mg2Si pn-junction photodiodes fabricated by thermal diffusion of Ag acceptor. The Ag concentration profiles and pn-junction depth in the samples annealed between 400 and 550 °C for 10min were studied by SIMS and EBIC. We observed two types of lattice diffusions with two different diffusion coefficients of which activation energies were approximately 0.97 and 0.71 eV. By comparing the observed pn-junction depth with the Ag concentration profiles, we determined the actual Ag concentrations at the pn-junction interface for annealed at 400, 450 and 480 °C.