FACET ROUGHNESS ANALYSIS FOR INGAN GAN LASERS WITH CLEAVED FACETS/

Atomic force microscope images reveal a root-mean-square roughness Del ta d = 16 nm for InGaN/GaN double-heterostructure laser structures wit h cleaved a-plane facets. The c-plane sapphire substrate cleaves clean ly along both the a and m planes. A theoretical model is developed whi ch shows that the power reflectivity of the facets decreases with roug hness by a factor of e(-16 pi 2(n Delta d/lambda 0)2), where n is the refractive index of the semiconductor and lambda(0) is the emission wa velength. Laser emission from the optically pumped cavities shows a TE /TM ratio of 100, an increase in differential quantum efficiency by a factor of 34 above threshold, and an emission line narrowing to 13.5 m eV. (C) 1998 American Institute of Physics. [S0003- 6951(98)00340-4].