II–VI Semiconductor blue-green laser device characteristics

Abstract

Threshold current densities and lasing wavelengths of both ZnSSe/ZnSe/ ZnCdSe and ZnMgSSe/ZnSSe/ZnCdSe lasers under short-pulse (100 ns) operation have been measured as a function of temperature. In the second structure, improved electrical confinement and a lower defect density leads to a better T 0 and a higher maximum lasing temperature. In these lasers a room-temperature pulsed threshold current density of 400 A/cm 2 has been obtained. Using ZnSe/ZnTe graded electrical contacts, a laser operating voltage of 6.5 V has been realized. Thermal resistances have been measured in ZnMgSSe/ZnSSe/ZnCdSe lasers. A value of 31 K W has been obtained in a 20 μm stripe laser of 600 μm length, mounted substrate-up. Both substrate-up and substrate-down mounted lasers meet the thermal continuous-wave lasing condition at room temperature. The relationship between stacking fault density and laser performance has been measured. Defect densities higher than 10 7 cm −2 significantly increase the lasing threshold. Characteristics of narrow-stripe gain-guided lasers have been measured. Clear changes are seen between short-pulse (100 ns) and longer pulse (800 ns) operation. A simple model that represents thermal index-guiding is used to explain the behavior. The antiguiding parameter is found to be about −1.1.