THEORETICAL-ANALYSIS OF THE THRESHOLD CURRENT-DENSITY IN GAN ALGAN STRAINED-QUANTUM-WELL LASERS WITH A MODULATION-DOPED STRUCTURE/

The dependence of the threshold current density on the doping type and dopant concentration in GaN/AlGaN modulation-doped (MD) strained quan tum well (QW) lasers is theoretically investigated. This investigation is based on a detailed band structure calculation using the tight-bin ding method. It is found that the threshold current density of GaN/AlG aN n-type MD-QW lasers can be reduced to 1/2-1/3 that of undoped laser s due to the reduced transparent injected carrier density. The thresho ld current in p-type MD lasers, however, increases because of decrease d carrier lifetime. These results show that n-type MD-QW lasers are mo re suitable for short-wavelength lasers based on III-V nitrides.