CdSe fractional-monolayer active region of molecular beam epitaxy grown green ZnSe-based lasers

This letter reports on the self-organized growth of nanoscale dot-like CdSe -based islands during molecular beam epitaxy of CdSe/ZnSe nanostructures wi th a CdSe thickness between 0.75 and 3.0 monolayers. An increase in the nom inal CdSe thickness results in a higher density of islands (up to 2 X 10(10 ) cm(-2)) and is accompanied by dramatic enhancement of the photoluminescen ce efficiency. The density of large relaxed islands appears to saturate at a value of (3-4) X 10(9) cm(-2). Room temperature (Zn, Mg)(S, Se)-based opt ically pumped lasers with an extremely low threshold (less than 4 kW/cm(2)) , as well as (Be, Mg, Zn)Se-based injection laser diodes using a single (2. 5-2.8) monolayer thick CdSe active region, both demonstrating significantly enhanced degradation stability, have been fabricated and studied. (C) 1999 American Institute of Physics. [S0003-6951(99)03804-8].