AbstractWe report on fabrication and characterization of cleaved laser facets and photoelectrochemically wet etched laser facets in III-Nitrides grown by MOVPE on c-plane sapphire. The roughness of the cleaved facets in the InGaN/GaN double heterostructure (DH) laser cavities with a 1000-Å-thick active region is ≈25 rim, while that of the wet etched GaN facets is ≈100 nm. A theoretical model is developed for the maximum allowable laser facet roughness, which yields a value of 18 nrm for uncoated GaN and 22 rm for the uncoated DH. Optically pumped laser action at room temperature is demonstrated in the cleaved DH laser cavities. 2 Above the incident threshold pumping power of 1.3 MW/cm2, the differential quantum efficiency increases by a factor of 34, the emission linewidth decreases to 13.5 meV, and the output becomes highly TE polarized. Wet chemical etching a 1-mm-long laser cavity into the GaN homostructure is found to increase the differential quantum efficiency by a factor of 2.
Generation of 16 Micrometer IR Laser by theOptical Pumping of CF4 Gas Molecules