ELECTRONIC BAND STRUCTURES AND OPTICAL GAIN SPECTRA OF STRAINED WURTZITE GAN-ALXGA1-XN QUANTUM-WELL LASERS

The electronic band structures, density-of-states, and optical gain sp ectra for wurtzite GaN-AlxGa1-xN quantum wells are studied theoretical ly based on the Hamiltonian derived using the k.p method. We investiga te the dependence of the optical gain and transparent current density on the well width, barrier height, and strain using a numerical approa ch with high accuracy. The mole fraction of Al in the barrier material is progressively increased to study the effects of quantum confinemen t and compressive strain. A higher Al mole fraction in the barrier lea ds to improvement of the TE optical gain and suppression of the TM opt ical gain. Furthermore, we demonstrate that a reduction of the well wi dth offers improved modal gain over all radiative current densities. W e also predict a transparent current density of 250 A/cm(2) for the Ga N-Al2Ga1-xN single quantum-well (QW) structure. Our results suggest th at a suitable combination of thin well width and large barrier height should be selected in improving the TE optical gain in wurtzite GaN-Al xGa1-xN single QW.