Low-threshold buried-ridge II-VI laser diodes

Blue-green (λ=511 nm) separate confinement laser structures based on lattice-matched MgZnSSe-ZnSSe-CdZnSe have been grown by molecular beam epitaxy. Wide stripe gain-guided devices have been fabricated from several such wafers. These devices exhibit room-temperature pulsed threshold current densities as low as 630 A/cm2 and threshold voltages less than 9 V. Using a novel self-aligned process that results in a planar surface, buried-ridge laser diodes have also been fabricated. These devices have demonstrated room-temperature threshold currents as low as 2.5 mA, which is more than a factor of 50 lower than that of any previously reported II-VI laser diode. Room-temperature operation at duty factors up to 50% has been demonstrated. The far-field patterns from these devices indicate single lateral mode operation, suitable for diffraction-limited applications, such as optical data storage.