A detailed characterization of the impurity centers which were involved in the photoluminescence of p-type material that was doped with As and Sb was reported. The photoluminescence spectrum was measured from 1.35eV, up to the band edge, and at temperatures ranging from 4.2 to 30K. It was found that, in addition to the usual broad photoluminescence line that was centered at 1.45eV and was present in undoped and doped samples, the present doped samples exhibited a new band near to 1.54eV. The latter had a fine structure that comprised 2 peaks whose intensities varied with temperature. The observed longitudinal optical phonon replicas which were associated with the zero-phonon lines at 1.45 and 1.54eV, respectively, were characterized by Huang-Rhys factors of 1.3 and 0.30. The various electron-hole recombination processes were explained in terms of a simple analytical model that related the position of the zero-phonon lines to the relative intensities of the phonon side-bands. This model accounted for a chemical shift in the defect centers, and described the effect of the charge carrier longitudinal optical phonon interaction. A comparison of theory and experiment indicated effective Bohr radii of aAs = 1.06nm, aSb = 1.03nm, and ionization energies of EAs = 0.058eV and ESb = 0.061eV. It was concluded that there also existed native shallow donors with a binding energy of 0.013eV, and deeper native acceptor complexes with an effective Bohr radius of 0.61nm and an ionization energy of 0.1572eV.

M.Soltani, M.Certier, R.Evrard, E.Kartheuser: Journal of Applied Physics, 1995, 78[9], 5626-32