InP p-type epitaxial layers grown with the addition of rare-earth elements for use in radiation detection

InP single crystal layers were grown by liquid phase epitaxy on semi-insulating InP:Fe and n-type InP:Sn substrates with Ce, Pr, Tm, Tm203 and Yb additions to the growth melt. Grown layers were examined by low-temperature photoluminescence spectroscopy, C-V and temperature dependent Hall measurements. An efficient purification due to rare earth (RE) admixture has been observed and all reported layers exhibit the change of electrical conductivity from n to p at certain RE concentration in the melt. The highest purifying effect has been found for Pr and Tm203, where the impurity concentration was decreased by up to three orders of magnitude and fine luminescence spectral features were revealed. Ce and Yb were found as dominant acceptor impurities responsible for n to p type electrical conductivity change, while the dominant acceptor responsible for the conductivity crossover in the case of Tm and Tm203 admixtures remains to be identified.