Pseudomorphically Grown Ultraviolet C Photopumped Lasers on Bulk AlN Substrates

Abstract

Optically pumped ultraviolet lasers were fabricated on low-defect-density bulk (0001) AlN substrates. AlxGa1-xN/AlyGa1-yN heterostructures were grown by metal–organic vapor phase epitaxy near atmospheric pressure. Time-resolved photoluminescence studies of the multiple quantum well emission show long decay times of 900 ps at room temperature and confirm the high structural quality of the epitaxial layers. Laser resonators with a length of about 1 mm were formed by cleaving the AlN crystal to obtain m-plane mirror facets. Lasing is demonstrated at a wavelength of 267 nm with a threshold power density as low as 126 kW/cm2 at room temperature. The laser emission was transverse electrically polarized.