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Bi, monoclinic, C12/m1 (No. 12), a = 6.67256(1) Å, b = 6.1108(2) Å, c = 3.30013(9) Å, β = 110.412(2)°, V = 126.1 Å3, Z = 4, R(P) = 0.118, R(I) = 0.087, T = 295 K, P = 2.54 GPa.

We study the time evolution of the internal temperature of GaN-based laser diodes in pulsed operation using time resolved spectroscopy. Time dependent emission spectra are compared to continuous-wave measurements at different temperatures to relate changes in the longitudinal mode spectrum to the internal temperature. From the different shift in emission center and longitudinal modes, two subsystems are identified which heat up on different time scales: the charge carrier plasma and the crystal lattice. While the lattice takes several microseconds to reach thermal equilibrium, the plasma heats up within 20 ns after the onset of the electrical pulse. This behavior is attributed to the small heat capacity of the charge carrier plasma compared to the crystal lattice. [ABSTRACT FROM AUTHOR]

A microscopic theory is used to analyze optical gain in InGaN/GaN quantum wells (QW). Experimental data are obtained from Hakki–Paoli measurements on edge-emitting lasers for different carrier densities. The simulations are based on the solution of the quantum kinetic Maxwell–Bloch equations, including many-body effects and a self-consistent treatment of piezoelectric fields. The results confirm the validity of a QW gain description for this material system with a substantial inhomogeneous broadening due to structural variation. They also give an estimate of the nonradiative recombination rate. [ABSTRACT FROM AUTHOR]