THEORETICAL PERFORMANCE OF WURTZITE AND ZINCBLENDE INGAN GAN QUANTUM-WELL LASERS/

The theoretical gain, radiative and Auger recombination rates, and thr eshold current densities of ideal wurtzite (WZ) and zincblende (ZB) 20 Angstrom In0.2Ga0.8N/70 Angstrom GaN multiple quantum well laser diod es are compared. We obtain upper bounds on device performance, which a re based on reliable calculations for both band structure and recombin ation dependent features and show (1) that the performance of present devices having the ZB and WZ structures are within 20% of each other i n InGaN/GaN, and (2) that present performance of the best currently av ailable devices is only a factor of 3-4 below the theoretical limit. R adiative recombination is far more important than Auger processes. The calculations are performed using a superlattice K.p formalism and den sity functional theory within the local-density approximation. The lat ter yields bulk zone-center energies, wave functions, and directly cal culated momentum matrix elements. (C) 1998 American Institute of Physi cs. [S0003-6951(98)02741-7].