MBE-grown laser diodes based on beryllium containing II-VI semiconductors

We focus on several aspects of our recent optimization of Beryllium-contain ing ZnSe-based laser diodes. By passivating the GaAs surface with a BeTe bu ffer, defect densities below 10(4) cm(-2) can be achieved. Structures with BeZnSe-ZnSe-strained layer superlattices in the waveguide regions show T-0 values of 366 K at room temperature and, consequently, laser operation up t o 140 degrees C due to an efficient electrical confinement by the superlatt ice waveguide. In order to circumvent the limitation concerning the band ga p ( < 2.85 eV) of the p-type claddings, the p-type doping of BeMgZnSe/BeTe short period superlattices has been investigated. The insertion of BeTe fra ctional monolayers is shown to increase the p-type doping beyond the limits usually set by compensation in high band gap BeMgZnSe. Theoretical calcula tions indicate that an asymmetric design of the band gap of the cladding la yers can reduce current overflow and also enable blue emission with the Ber yllium-based material system. (C) 1999 Elsevier Science B.V. All rights res erved.