Optical properties of InP layers prepared with the addition of Ce, Tm and Lu in the growth melt

Abstract

InP single crystals were grown by liquid phase epitaxy on semi-insulating InP:Fe and n-type InP:Sn substrates with cerium, thulium and lutetium additions to the growth melt. Grown layers were examined by low-temperature photoluminescence spectroscopy and C-V measurements. Layers prepared with the addition of Ce and Tm exhibit the change of electrical conductivity from n to p, while those grown with Lu admixture remain n-type. Ce has been found to be incorporated into the InP lattice and sharp luminescence arising from 2 F 7/2 → 2 F 5/2 inner shell transitions of Ce 3+ at 3600 nm was detected. The highest purifying effect due to RE addition has been found for Tm admixture, where the impurity concentration was decreased by three orders of magnitude and fine spectral features were revealed by photoluminescence spectroscopy. The addition of Tm into the growth melt enables to prepare thick and pure InP layers of p-type conductivity -a material promising in the context of semiconductor radiation detectors.