Lasing in the vertical direction in quantum-size InGaN GaN multilayer heterostructures

Lasing is discovered in the direction perpendicular to the surface in quant um-size InGaN/GaN multilayer heterostructures grown by vapor-phase epitaxy. At high excitation densities one of the modes in the luminescence spectrum , which is modulated by modes of the Fabry-Perot cavity formed by the GaN/a ir and GaN/sapphire-substrate interfaces, is sharply amplified and begins t o dominate the spectrum. The dependence of the luminescence intensity on pu mp density has a clearly expressed threshold character. The threshold excit ation density in the vertical direction is 5-6 times greater than the stimu lated-emission threshold for observation from an end surface of the structu re. The gain coefficient in the active region at the threshold for surface- emitting lasing is estimated as 2 x 10(5) cm(-1). The interaction between t he cavity modes and the gain spectrum is detected in the form of displaceme nt (by up to 2.6 nm) of modes on the short-wavelength edge of the luminesce nce spectrum toward higher photon energies. The characteristic temperature (T-0) measured in the range from 16 to 120 K is 480 K. At higher temperatur es T-0 = 70 K. (C) 1999 American Institute of Physics. [S1063-7850(99)01706 -1].