Study of laser threshold temperature sensitivity in optically pumped GaN epilayers

Abstract

On the base of experimental spontaneous emission spectra measured at laser threshold the temperature dependencies of the radiative Rsp and nonradiative Q recombination rates as well as the spontaneous emission internal quantum efficiency ηsp for optically pumped wurtzite GaN=Al 2O3 epilayers have been calculated. The recombination rate induced by the amplified luminescence Rlum was taken into account. It is shown that the main reason of the increasing threshold pump rate R p with temperature T for the GaN-based compounds is a substantial rise of the nonradiative recombination rate. The portion of Q in Rp exceeds 80-90%. The contributions of Rsp and Rlum in Rp amount to several percents. The ηsp value is of 0.12-0.18 within the temperature interval of 300-450 K. Further increase in T leads to an abrupt decrease in ηsp down to 0.06 at 517 K. © 2002 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.