Final LDRD report : science-based solutions to achieve high-performance deep-UV laser diodes.

Abstract

We present the results of a three year LDRD project that has focused on overcoming major materials roadblocks to achieving AlGaN-based deep-UV laser diodes. We describe our growth approach to achieving AlGaN templates with greater than ten times reduction of threading dislocations which resulted in greater than seven times enhancement of AlGaN quantum well photoluminescence and 15 times increase in electroluminescence from LED test structures. We describe the application of deep-level optical spectroscopy to AlGaN epilayers to quantify deep level energies and densities and further correlate defect properties with AlGaN luminescence efficiency. We further review our development of p-type short period superlattice structures as an approach to mitigate the high acceptor activation energies in AlGaN alloys. Finally, we describe our laser diode fabrication process, highlighting the development of highly vertical and smooth etched laser facets, as well as characterization of resulting laser heterostructures. 4 ACKNOWLEDGMENTSThe authors gratefully acknowledge Blythe Clark, and Qiming Li for providing assistance in materials characterization. We appreciate the support of managers Dan Barton (project manager), Robert Biefeld, and Jerry Simmons throughout this work.5