LASER ACTION IN GAN PYRAMIDS GROWN ON, (111)-SILICON BY SELECTIVE LATERAL OVERGROWTH

Laser action was observed in GaN pyramids under strong optical pumping at room temperature. The pyramids were laterally overgrown on a patte rned GaN/AlN seeding layer grown on a (111) silicon substrate by metal -organic chemical vapor deposition. Each pyramid had a 15-mu m-wide he xagonal base and was on average 15 mu m in height. The pyramids were i ndividually pumped, imaged, and spectrally analyzed through a high-mag nification telescope system using a high-density pulsed excitation sou rce. Under high levels of optical pumping, multimode laser at room tem perature was observed. The integrated emission intensity for both spon taneous and lasing peaks was studied as a function of excitation power density. The effects of pyramid geometry and short-pulse excitation o n the multimode nature of laser oscillations inside of the pyramids is discussed. This study suggests that GaN microstructures could potenti ally be used as pixel elements and high-density two-dimensional laser arrays. (C) 1998 American Institute of Physics. [S0003-6951(98)02742-9 ].