Growth and luminescence properties of GaP:N and GaP₁₋xN_x

Nitrogen‐doped GaP and P‐rich GaP_1−xN_x alloys (x<0.03) exhibiting 77 K photoluminescence (PL) in the yellow–green to red portion of the visible spectrum have been grown on GaP substrates by gas source molecular beam epitaxy. The growth of these compounds was accomplished using gaseous NH₃ and PH₃ and solid Ga as the source materials. In samples with nitrogen concentration [N] < 10²⁰ cm⁻³, the dominant emission occurred at 569 nm, corresponding to the isoelectronic trap NN₁. The PL intensity was greatest for [N]≂ 10²⁰ cm⁻³. As the nitrogen concentration was increased beyond this value, a monotonic red shift was observed in the emission wavelength, while the intensity generally decreased with increasing [N]. The red shift in the band edge is explained in terms of severe bowing in the compositional dependence of the indirect band gap for the GaP_1−xN_x system, as predicted by the dielectric theory of electronegativity.