Temperature dependence of the InP band gap from a photoluminescence study

A set of parameters for the temperature dependence of the direct band gap of InP has been determined by fitting the excitonic recombination energy in the photoluminescence (PL) spectra between 2 and 250 K. We have used high-quality InP samples grown by chemical beam epitaxy. The superfluid-helium-temperature PL spectra are characterized by strong excitonic transitions (the excited state n=2 of the exciton is observed too) from which we have determined the binding energy of the exciton (${\mathit{E}}_{\mathit{b}}$=5.3 meV) and the band-gap energy (${\mathit{E}}_{\mathit{g}}$=1.4239 eV at 1.3 K). The variable-temperature PL spectra are characterized by excitonic transitions for temperatures as high as 250 K. The expression ${\mathit{E}}_{\mathit{g}}$(T)=1.4539-0.0359{1+2/exp[(209 K)/T]-1} eV, which extrapolates to ${\mathit{E}}_{\mathit{g}}$=1.347 eV at 300 K, is proposed for the temperature dependence of the InP band gap over the temperature range 0–300 K.