Computer-aided design of double heterojunction GaAlAs laser diodes - Application to the manufacture of devices emitting in the visible spectrum

CAD techniques for the design of semiconductor lasers functioning in the visible spectrum are investigated, taking into account minima in the conduction band and the presence of heterojunction barrier defects. The theoretical basis of double heterojunction lasers is reviewed, and a generalized relation is defined between the threshold current density and the optical gain for GaAlAs diode lasers. Techniques for manufacturing the lasers are described, noting steps which can ameliorate the mechanisms of radiative transitions in visible wavelengths and the difficulties in tailoring the barrier heights. Attention is given to the active zone, the roles of confinement and injection in the heterojunctions, and the characteristics of an oscillating optical cavity. Finally, a numerical model is developed for CAD of the lasers with account taken of the creation of electron-hole pairs and numerical simulation of the electric behavior of double heterojunction structures. It is concluded that optimized performance has not yet been obtained for GaAs heterojunction devices, and further examination of the behavior of aluminum in the heterojunction structure is recommended.