Optically pumped InGaN/GaN lasers with wet-etched facets

Optically pumped laser action is demonstrated in InGaN/GaN double heterostr ucture lasers with wet-etched facets. The facets are formed by a two-step e tching process which creates vertical facets with less than 5 nm roughness. The first step, photoenhanced electrochemical wet etching, is used to defi ne the laser cavities. The second step reduces the facet roughness by cryst allographic wet chemical etching. Lasing is demonstrated by an increase in the differential quantum efficiency, linewidth narrowing, and strongly pola rized output above threshold. The threshold varies with cavity length from 2.4 MW/cm(2) for 500 mum cavities to 23 MW/cm(2) for 50 mum cavities. A mod al loss of 15 cm(-1) is deduced from an analysis of the threshold pumping p ower as a function of cavity length. (C) 2000 American Institute of Physics . [S0003-6951(00)00852-4].