Femtosecond pump-probe spectroscopy and time-resolved photoluminescence of an InxGa1-xN/GaN double heterostructure - art. no. 195302

摘要

We report a study of the carrier dynamics in an In0.18Ga0.82N thin film photoexcited well above the band gap using nondegenerate pump-probe spectroscopy and time-resolved photoluminescence (TRPL) for carrier densities ranging from 10(17) to 10(19) cm at 10 K. At carrier densities greater than 4 x 10(18) cm(-3), optical gain occurs across the entire band tail region after similar to2.5 ps time delay, when the hot carriers completely fill these states. From TRPL measurements performed in the surface emission geometry, we observed stimulated emission (SE) with a similar to 28 ps decay time. Since this SE has a threshold density of 1 x 10(18) cm(-3), which is larger than the total density of localized states, and the SE spectra at early time delays are quite different from the spontaneous emission spectra. we attribute the SE to the recombination of an electron-hole plasma from renormalized band-to-band transitions. [References: 34]