OPTIMIZING ALXGA1-XN SEPARATE-CONFINEMENT HETEROSTRUCTURE LASERS WITHLARGE BAND DISCONTINUITIES

Two-dimensional simulations were performed to optimize the waveguiding region's aluminum composition of an AlGaN/GaN separate confinement he terostructure (SCH) laser with large band discontinuities. Results dem onstrate that the active region's thickness, waveguiding regions' thic kness, and the material composition of the waveguiding region should b e optimized, based on losses of the materials in the structure. Result s also demonstrate that the threshold current of a SCH laser may be la rger than that of a double heterostructure laser. The increase is caus ed by a competition between the active region and the waveguiding regi on which has a parasitic effect on the laser's modal gain because of t he waveguiding region's slightly larger band gap, so that below the la sing threshold, photon emission and population inversion can occur in both regions. At the minimum threshold current the structure is optimi zed to strongly confine both the guided optical mode and the charge ca rriers responsible for the gain. (C) 1997 American Institute of Physic s.