Blue-green ZnSe lasers with a new type of active region

We report the results of an experimental study of molecular-beam epitaxy of ZnSe-based laser heterostructures with a new structure of the active regio n, which contains a fractional-monolayer CdSe recombination region in an ex panded ZnSe quantum well and a waveguide based on a variably-strained, shor t-period superlattice are reported. Growth of a fractional-monolayer CdSe r egion with a nominal thickness of 2-3 ML, i.e., less than the critical thic kness, on a ZnSe surface (Delta a/a similar to 7%) leads to the formation o f self-organized, pseudomorphic, CdSe-enriched islands with lateral dimensi ons similar to 10-30 nm and density similar to 2x10(10) cm(-2), which serve as efficient centers of carrier localization, giving rise to effective spa tial separation of defective regions and regions of radiative recombination and, as a result, a higher quantum efficiency. Laser structures for optica l pumping in the (Zn, Mg) (S, Se) system with a record-low threshold power density (less than 4 kW/cm(2) at 300 K) and continuous-wave laser diodes in the system (Be, Mg, Zn) Se with a 2.5 to 2.8-ML-thick, fractional-monolaye r CdSe active region have been obtained. The laser structures and diodes ha ve an improved degradation resistance. (C) 1999 American Institute of Physi cs. [S1063-7826(99)02409-6].