Decay of green photoluminescence in GaP:Zn,O

A low-temperature spectrally resolved study was made of the decay characteristics of green emission in liquid-phase epitaxially grown GaP:Zn,O. An analysis of the steady-state and transient characteristics of this emission is shown to be consistent with a proposed model. The dependence of the pair transition rate on the donor-acceptor pair separation is discussed with reference to a theoretical model based upon the overlap of donor and acceptor wave functions within the effective-mass approximation. A previously reported value of 12.2 Å for the zinc acceptor (shallow impurity) effective Bohr radius in GaP is confirmed. The analysis provides a value of 2×${10}^5$ ${\mathrm{s}}^{\mathrm{-}1}$ for the converging-limit pair recombination rate for the zinc-sulfur donor-acceptor pairs responsible for the green emission band. The influence of donor-acceptor pair distribution and the strengths of phonon-assisted- versus unassisted-transition rates on the measured spectra are discussed.