Emission wavelength and cavity design dependence of laser behaviour in HgCdTe heterostructures

Abstract

Optical gain and laser emission have been studied in molecular beam epitaxy grown HgCdTe heterostructures emitting in the 1.9–3.5 μm wavelength range. Laser emission is observed up to room-temperature for samples emitting in the 1.9–2.5 μm range. The use of quantum wells and of a graded index in the barriers has allowed a significant reduction of the laser thresholds as compared to a separate confinement heterostructure of similar composition: thresholds as low as 53 W cm−2 at 20 K and 295 W cm−2 at 100 K have been obtained. As the emission wavelength increases, the characteristic temperature T0 observed at high temperature becomes less favourable: 63, 45 and 30 K for the 1.9, 2.5 and 3.5 μm emitting samples, respectively. For this last sample, laser emission has been observed only up to 150 K. This degradation of the lasing condition is interpreted as being due to the Auger effect, which becomes increasingly important as the band gap decreases.