Size-enhanced, coherent photoluminescence from CdS-ZnO nanocomposite thin film

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We show that the photoluminescence emitted from a dense, two-component ensemble of quantum dots is significantly higher than that from quantum dots of either of the two pure systems (CdS and ZnO). The semiconductor nanocomposite, in which the characteristic grain size of each species was 2-3 nm, was deposited directly on Si wafers by high-pressure magnetron sputtering. It exhibits a single, relatively sharp optical absorption edge. Further, using the classical Young's double slit experiment we show - possibly for the first time - that the emitted photoluminescence has significant spatio-temporal coherence, a fact that would be crucial for their use in quantum information processing as well as for lasing action from light-emitting particles.