Fabrication of freestanding GaN by HVPE and optically pumped stimulated emission at room temperature

Abstract

Single-crystalline freestanding GaN, having a current maximum size of 10 × 10 mm 2 and a thickness of 350 µm, was fabricated by hydride vapour phase epitaxy (HVPE) growth of thick-film GaN on a sapphire substrate and subsequent removal of the host sapphire substrate. We also observed the room-temperature optically pumped stimulated emission (SE) from a 1 mm width cleaved cavity prepared from freestanding GaN. At a maximum power density of 2 MW cm −2 , the peak energy and FWHM of SE were 3.318 eV and 8 meV, respectively. The threshold pumping power density for the one set of SE was 0.37 MW cm −2 , and the output becomes highly TE-polarized.