A quasi-continuous wave, optically pumped violet vertical cavity surface emitting laser

Summary form only given.The InGaN/GaN multiple quantum well (MQW) heterostructure has become the standard active medium in blue and violet nitride edge-emitting diode lasers. Their gain characteristics suggest that vertical-cavity surface-emitting laser (VCSEL) operation may also be possible, although with increasing indium concentration (x>0.1) compositional anomalies in this non-random alloy create undesirable localized states, which reduce peak gain. We report quasi-CW operation of an optically pumped InGaN MQW VCSEL near /spl lambda/=403 nm, up to room temperature, equipped with a pair of low-loss dielectric DBR mirrors forming the optical cavity. A fabrication technique was used that includes liftoff of the nitride heterostructure from its sapphire surface and subsequent removal of the GaN buffer layer by ECR etching, prior to the completion of the microcavity. The optical structures reached quality factors Q/spl sim/1000, with the active region composed of /spl sim/20 In/sub 0.1/Ga/sub 0.9/N QWs. The OMVPE growth was optimized to virtually eliminate crack formation and to provide a high degree of optical flatness despite the presence of AlGaN cladding layers. We have found that good morphology is crucial to the VCSEL operation. AFM studies of as-grown and etched surfaces indicated a mean roughness of approximately 1 nm.