Resonant Gain in ZnSe Structures with Stacked CdSe Islands Grown in Stranski-Krastanov Mode

The optical gain of CdSe/ZnSe structures containing stacks of islands grown in the Stranski-Krastanov mode was studied. The islands have a lateral size of approximate to 16 nm and a small height-to-width ratio. Cd contents of approximate to 70% were estimated from transmission electron microscopy investigations. The radiative recombination of excitons localised in the islands leads to a broad emission band around 2.4 eV. At low temperatures a resonant gain of up to 300 cm(-1) generated by localised transitions was found.