Exciton transfer at low temperature in GaxIn1−xP:N and GaAs1−xPx:N

Abstract

The time-resolved luminescence of excitons bound to isolated nitrogen traps in ${\mathrm{Ga}}_{\mathrm{x}}$ ${\mathrm{In}}_{1\mathrm{-}\mathrm{x}}$P (x>0.96) has been investigated under resonant and above-the-band-gap picosecond laser excitation at T=5 K. We observe the dynamics of exciton tunneling both between and within the two main bands ${\mathrm{N}}_{\mathrm{x}}$ and $A_0$ seen in the alloy spectra. The results are a direct proof of the very efficient transfer which occurs for excitons bounds to isolated nitrogen atoms surrounded by four Ga near neighbors (${\mathrm{N}}_{\mathrm{x}}$ band) to nitrogen atoms with a three-Ga–one-In environment ($A_0$ band). An analytic model for these transfer mechanisms fits the measured time evolution of the luminescence spectra for ${\mathrm{Ga}}_{\mathrm{x}}$ ${\mathrm{In}}_{1\mathrm{-}\mathrm{x}}$P:N. The same model also describes previously published data for ${\mathrm{GaAs}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{P}}_{\mathrm{x}}$:N.