Photoluminescence of undoped GaxIn1−xP alloys

Changes in photoluminescence spectra at low temperatures (2 to 20 °K) are reported of non-intentionally doped GaxIn1—xP solution-grown alloys in the whole range of compositions. Below the Γ15-X1 band cross-over composition (x = 0.65 ± 0.03), the spectra are similar to those of InP, with a tendency to shift to lower energies relatively to the bandgap. For larger values of x, some lines are observed which differ from those of GaP. The value of Γ15–X1 gap in InP is deduced to be (2.30 ± 0.04) eV at 4.2 °K. A pair transition line is observed throughout the composition range, with discontinuities of the half-width and rate of excitation shift at the cross-over composition.