Highly efficient room-temperature ultraviolet (UV) luminescence is obtained in heterostructures consisting of10-nm-thick ultrathin ZnO films grown on Si nanopillars fabricated using self-assembled silver nanoislands as anatural metal nanomask during a subsequent dry etching process. Atomic layer deposition was applied fordepositing the ZnO films on the Si nanopillars under an ambient temperature of 200�C. Based on measurements ofphotoluminescence (PL), an intensive UV emission corresponding to free-exciton recombination (approximately3.31 eV) was observed with a nearly complete suppression of the defect-associated, broad-range visible emissionpeak. As compared to the ZnO/Si substrate, the almost five-times-of-magnitude enhancement in the intensity of PL,which peaked around 3.31 eV in the present ultrathin ZnO/Si nanopillars, is presumably attributed to the highsurface/volume ratio inherent to the Si nanopillars. This allowed considerably more amount of ZnO material to begrown on the template and led to markedly more efficient intrinsic emission.
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