DRY-ETCHING AND CHARACTERIZATION OF MIRRORS ON III-NITRIDE LASER-DIODES FROM CHEMICALLY ASSISTED ION-BEAM ETCHING

Vertical mirrors have been fabricated with chemically assisted ion bea m etching (CAIBE) on OMVPE grown InGaN/AlGaN laser diode structures. A FM measurements show that smooth vertical sidewalls are obtained which exhibit a root mean squared (rms) roughness of only 40-60 Angstrom. T he inclination angle of the etched mirrors is within +/- 2 degrees of vertical, as SEM studies indicate. Photopumping measurements reveal th at the reflectivity of the etched mirrors corresponds to 60-70% of the value for an ideal GaN/air interface. The reduced reflectivity may be due to surface roughness, a slight tilt In the facet angle, and the e xcitation of higher-order transverse waveguide modes in the laser stru cture. (C) 1998 Elsevier Science B.V. All rights reserved.