Prediction of low threshold current density in InGaN-AlGaN quantum wire lasers due to excitonic transitions

摘要

Abstract: The exciton binding energies in InGaN-AlGaN quantum wire are calculated to be 30-60 meV as wire width reduces from 150 angstrom to 50 angstrom. This high binding energy results in large exciton densities, making optical transitions due to excitons dominant over free electrons and holes. Optical gain and threshold current densities in InGaN-AlGaN based multiple quantum wire lasers are computed including the effect of strain and dislocations. The calculated threshold current density for a defect free compressively-strained quantum wires laser, such as realized on sapphire or SiC substrate, are shown to yield an ultra-low threshold current density of 148 A/cm$+2$/ and 1,600 A/cm$+2$/ in the presence of dislocations. The exciton transitions assist in lowering the threshold current density which is adversely affected by the presence of dislocations and surface states. This shows an improvement over our computed value as well as the experimental data reported by Nakamura et. al. for quantum well lasers. !14