Room-temperature deep-state emission spectra, radiative efficiency, and lifetime of some GaP:Te,N crystals

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Abstract
Photoluminescent spectral measurements are presented on a series of GaP:Te,N crystals with varying net donor concentration. The maximum near‐bandedge emission internal quantum efficiency in these crystals had been shown to be 0.6% at 1017 cm−3 net donor concentration. We show that the radiative deep‐state recombination component above 1.2 eV accounts for only 3% of the total recombination in the material with the highest green efficiency. Two infrared emission bands are observed in our Te‐ and S‐doped LPE material at ∼1.2 and ∼1.6 eV. The relative and absolute strength of these two bands vary with both ND−NA and nitrogen concentration [N]. Simplified analysis of the saturation behavior of one of the infrared bands and the green emission showed that at low‐excitation levels where this center is unsaturated, 42% of the total recombination was flowing through the responsible center. Thus the dominant recombination proceeds nonradiatively. However, at normal LED operation currents these centers should be saturated and thus responsible for only a small amount of the recombination.