Effects of hydrogenation and annealing on the shallow donor-band recombination in In-doped CdTe epitaxial layers grown on p-CdTe (211) substrates

Abstract

Photoluminescence (PL) measurements have been performed on as-grown, annealed, and hydrogenated In-doped CdTe epitaxial films grown on p-CdTe (211) substrates by using molecular beam epitaxy in order to investigate the annealing and the hydrogenation effects on the behavior of the shallow donor-band recombination (D,h) peak. The smaller full width at half maximum (FWHM) values of the (D,h) emission lines in the annealed and the hydrogenated epilayers show that the crystallinity of the In-doped CdTe epilayers has been improved due to the annealing and the hydrogenation treatments. The inhomogeneous broadening of the FWHM values of the (D,h) peaks in the In-doped CdTe epilayers might be related to a change from correlated distributions of the electrons and the holes at low temperatures to random distributions at high temperatures. The concentrations of the shallow donors and the compensation coefficients were estimated from the dependence of the FWHM of the (D,h) lines on the temperature by using PL spectra. These results indicate that the crystallinity and the electrical properties of the In-doped CdTe epilayers are affected significantly by the annealing and the hydrogenation treatments.