Thermal stability of ZnMgSSe/ZnSe laser heterostructures

Optically pumped lasing and photoluminescence of ZnMgSSe/ZnSe quantum wells grown by metal-organic vapour phase epitaxy were studied in the temperatur e interval of 13-650 K. Thermal annealing at high temperatures deteriorated the lasing properties which, however, could be almost completely recovered by subsequent optical excitation above the lasing threshold. The technique of spectrum imaging in a transmission electron microscope with an energy f ilter and a two-dimensional detector was applied to ZnMgSSe/ZnSe multiple q uantum well laser structures. It was found that the main degradation mechan ism of ZnMgSSe/ZnSe quantum well heterostructures at temperatures higher th an 450 K is the diffusion of S atoms from the barriers into the quantum wel ls which leads to increasing point defect concentrations in the active laye rs of the Lasers. It was established that stimulated lasing decreases the d efect concentration and reduces the laser threshold in the optically pumped ZnMgSSe/ZnSe quantum well lasers after their thermal degradation at 450-65 0 K.