Enhancement of intrinsic emission from ultrathin ZnO films using Si nanopillar template

Abstract

Highly efficient room-temperature ultraviolet (UV) luminescence is obtained in heterostructures consisting of 10-nm-thick ultrathin ZnO films grown on Si nanopillars fabricated using self-assembled silver nanoislands as a natural metal nanomask during a subsequent dry etching process. Atomic layer deposition was applied for depositing the ZnO films on the Si nanopillars under an ambient temperature of 200°C. Based on measurements of photoluminescence (PL), an intensive UV emission corresponding to free-exciton recombination (approximately 3.31 eV) was observed with a nearly complete suppression of the defect-associated, broad-range visible emission peak. 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 high surface/volume ratio inherent to the Si nanopillars. This allowed considerably more amount of ZnO material to be grown on the template and led to markedly more efficient intrinsic emission.

Enhanced photoluminescence from SiOx–Au nanostructures

“…One is to synthesize luminescent materials with high surface to volume ratios. 19,20 For silicon oxide, the research results showed that most of its PL emission resulted from defects in or on the surface of the nanostructures. [21][22][23] SiO x nanostructures with a large surface to volume ratio tend to have a higher PL emission efficiency since the surface of the material is very active and easily forms defects, especially at the nanoscale.…”

Enhanced electrical properties and field emission characteristics of AZO/ZnO-nanowire core–shell structures

“…The pulse duration of the ultrathin AZO film was still 10 ms. N 2 served as the purging gas with its pressure set to 1 Torr. These deposition procedures were used to deposit AZO films on the surface of ZnO-NWs with total cycles numbering 16,32,48,64,104,200,304, and 400 ALD cycles (all total cycles are divisible exactly by 8). AZO films from ALD provided a superior coating with a high aspect ratio for enhanced electrical properties.…”

“…13 With the strong step coverage of ALD techniques, a thin layer of ZnO or TiN can be uniformly coated, via ALD, on 1D Si nanostructures to enhance the field-emission properties. 13,15,16 AZO is a transparent conducting oxide with useful electrical properties (B10 À4 O cm) and large transmittance (B92%), which makes it an attractive material for transparent conducting electrodes for photoelectric devices. [17][18][19] AZO has been considered an ideal candidate to replace indium tin oxide (ITO) that is applied in photoelectric devices such as light-emitting diodes (LEDs), transparent electronics, solar cells and gas sensors.…”

Cathodoluminescence study of defects in thermal treatment of zinc titanate thin films deposited by a cosputtering process

“…Lin et al have found that based on the composite of ZnO nanorods and TiO 2 , the band edge emission of ZnO nanorods can be enhanced up to 120 times . For optoelectronic devices, doped ZnO films have also been deposited . The properties of the ZnO–TiO 2 system that are responsible for the luminescence performance therefore becomes an interesting issue.…”