Abstract

Cadmium telluride films (~2µm) homo-epitaxially grown by molecular beam epitaxy (MBE) have been observed to undergo stimulated emission (SE) at 10 K. The samples were photoexcited using a 8 ns, 10-Hz pulsed dye laser, using both side-pumping and backscattering geometries. Stimulated emission occurred at the low energy edge and just below the exciton band in the region from 1.570 to 1.590 eV. The effect of the pump power density on the evolution of the SE was studied, including threshold, gain, and saturation behavior. The samples showed competition among the stimulated peaks, with a lower energy peak arising and superceding the higher energy emission in some samples with an increase in the excitation power density. Red-shifting of this lower energy SE peak was observed, while broadening was seen in all samples at high pump densities. The differing behavior between samples has been ascribed to the differences in the details of the impurity states in the samples. All samples showed stimulated emission at ~1.580 eV, which suggests an intrinsic defect related transition. The excitation wavelength dependence was studied using high power photoluminescence excitation near the bandgap. Resonances between multiple LO phonons, the excitons, and bandgap were observed.

© 1990 Optical Society of America