Cleaved-facet group-III nitride lasers.

摘要

Cleaved-facet semiconductor lasers are preferred to etched-facet lasers due to the ease with which they can be manufactured, the flatness of the resultant facet, and the freedom from processing tolerances. Unfortunately, the most promising epitaxial layer/substrate pairing for blue-emitting semiconductor lasers is (0001) InGaN-based QWs grown on (0001) sapphire substrates. In this thesis, I detail the fabrication of cleaved facets for InGaN-based QW lasers by three methods: (1) wafer bonding the InGaN QWs to GaAs or InP and use the cleave planes of the cubic material to force the break of the GaN along desired planes, (2) growing InGaN QWs on (1120) sapphire and thin the substrate to 50 mum before cleaving, and (3) using gold bonding to join InGaN QWs to GaAs and use laser ablation to remove sapphire substrate before cleaving. Lasers have been successfully fabricated by the second method. LEDs have been fabricated by the third method, but degradation of the active region by the laser ablation process prohibits lasing in these devices. Device design improvements from optical, electrical, and thermal models are presented. Comparisons of device structures and geometries are made on the basis of these models.