High Purity p-type InP Grown by LPE with Rare-Earth Admixtures

Specific features of rare-earth-oxides (PrO_x, TbO_x , Tm₂O₃, Gd₂O₃ and Eu ₂O₃) and Gd are employed to improve physical properties of InP layers. The InP layers were grown by liquid phase epitaxy (LPE) on (100)-oriented single crystal InP substrates with rare-earth element (RE) addition to the growth melt. The surface morphology and defect density was monitored by optical and scanning electron microscopy, the evaluation of electrical properties was gained from C-V characteristics and Hall measurements, and the low-temperature photoluminescence spectroscopy was used to study the optical properties. Significant improvement of all studied layer parameters with increasing amount of RE in the melt was observed right to critical value of RE concentration. The residual impurity concentration was reduced by up to three orders of magnitude, photoluminescence spectra were markedly narrowed and fine spectral features were resolved. The conductivity changed from n- to p-type when certain limit of RE concentration in the melt was exceeded for majority of studied REs