Optical properties of the main electron-irradiation-induced defects inp-type InP: Comparison with calculations for the isolated and acceptor-paired phosphorus vacancy

Optical capacitance spectroscopy and thermal annealing of defects have been used to study both the electron traps ${\mathrm{EP}}_1$,${\mathrm{E}}_{11}$ and the dominant hole traps (${\mathrm{H}}_3$-${\mathrm{H}}_4$-${\mathrm{H}}_4^{\prime }$) produced by low-energy electron irradiation in Zn-doped p-type InP. This shows that the 1.1-eV onset in the photoionization cross sections (PCS's) previously attributed to (${\mathrm{H}}_3$-${\mathrm{H}}_4$) is actually due to the unrelated electron trap ${\mathrm{EP}}_1$. The true PCS's ${\mathrm{\sigma }}_{\mathrm{p}}^0$ of (${\mathrm{H}}_3$,${\mathrm{H}}_4$) are compared with PCS tight-binding Green's function calculations to test the earlier proposal that the (${\mathrm{H}}_2$-${\mathrm{H}}_3$-${\mathrm{H}}_4$-${\mathrm{H}}_4^{\prime }$,${\mathrm{E}}_{11}$) series might arise from different states of (${\mathrm{V}}_{\mathrm{P}}$-Zn) complexes. The model yields an effective agreement as concerns both the energy location of the hole-levels series in the forbidden gap and the vanishingly small contribution to the PCS's of the four equivalent L valence-band minima. The proposal that ${\mathrm{E}}_{11}$ might correspond to the ionization of an e state of the ${\mathrm{V}}_{\mathrm{P}}$-Zn complex also agrees with the experimental observation of both optical transitions to the valence band and to the conduction band but cannot account for the midgap position of ${\mathrm{E}}_{11}$.