Recombination processes involving Zn and N inGaAs1−xPx

Photoluminescence experiments have shown that for $\mathrm{Ga}{\mathrm{As}}_{1-x}{\mathrm{P}}_x:\mathrm{N},\mathrm{Zn}$ in the direct composition region $x\lesssim x_c\equiv 0.46, 77$ °K) the dominant radiative recombination process involves an electron bound to the N isoelectronic trap and a hole bound to the ionized Zn acceptor. In the indirect composition region ($x>\mathrm{}{x}_c$), the influence of the Zn impurity on recombination is observed to decrease, and the dominant recombination process becomes the decay of bound excitons. This change in the rediative recombination process can be explained in terms of calculated optical-absorption coefficients for the competing transitions. The relative strengths of these absorption coefficients are compared to the shift (normalized) of the emission spectra obtained on $p$-type samples relative to the emission spectra obtained on $n$-type samples from the same $\mathrm{Ga}{\mathrm{As}}_{1-x}{\mathrm{P}}_x:\mathrm{N}$ crystal prior to Zn diffusion.