High pressure studies of mid-infrared type-II "W" diode lasers at cryogenic temperatures

Using high hydrostatic pressure and spontaneous emission characterisation techniques we have investigated the important loss processes in type-II "W" diode lasers, which emit at 3.24 mu m at 78 K. Our studies indicate that Auger recombination involving the excitation of holes in the valence band and/or inter-valence-band absorption may contribute to the temperature sensitivity of these devices, even at cryogenic temperatures. Defect/impurity related recombination, which was of concern in these structures does not appear to make a significant contribution to the threshold current over the temperature and pressure ranges investigated.