ELASTIC STRAIN AND ENHANCED LIGHT-EMISSION IN DRY-ETCHED SI SI1-XGEX QUANTUM DOTS/

Quantum dots of 50 similar to 60 nm diameter fabricated from both Si/S i1-xGex (x = 0.1 similar to 0.3) strained layer superlattices and a st rain symmetried Si-9/Ge-6 superlattice were investigated by a combinat ion of Raman scattering, photoluminescence, and electroluminescence sp ectroscopy. It was found that, in addition to an enhanced luminescence intensity of the dots by over two orders of magnitude and improved lu minescence quenching temperature, all of the nanostructure dots have r esidual built-in elastic strains, which are of the order of similar to 50% of the values in corresponding pseudomorphic heterostructures. Th is result suggests a possible mechanism for explaining the huge enhanc ement of the optical efficiency in our luminescence measurements.