1,721,067 research outputs found
Electroluminescence in n-ZnO nanorod arrays vertically grown on p-GaN
No full textElectrolurninescent (EL) devices (see Figure) have been fabricated using n-ZnO nanorod arrays grown on p-GaN epilayers. Simple heteroepitaxial growth yields vertically aligned ZnO nanorods with an abrupt interface on GaN. The p-n heterojunction EL device shows a high current density and strong electroluminescence even at a reverse-bias voltage of 3 V.X11646sciescopu
Compensation model for n-type GaN
No full textThe defect structure for unintentionally doped and deliberately Se-doped, n-type GaN was investigated, For impurity doping, Se was incorporated into GaN films during vapor phase epitaxial growth. Both nominally undoped and Se-doped. n-type GaN films were highly compensated as determined by the Hall effect measurements and photoluminescence spectroscopy. It was also found that the compensation by acceptors increases with increasing Se doping concentration. Based upon these experiments and the theoretical calculations, a defect compensation model for n-type GaN was developed.X111sciescopu
Low-temperature epitaxial growth of cubic silicon carbide on Si(100) for submicron-pattern fabrication
No full textSiC films were selectively grown on patterned SiO2/Si(100) substrates using supersonic molecular jet epitaxy. For film growth, we employed methylsilane seeded in a carrier gas (He or H-2) as a reactant gas. Due to the high translational kinetic energy of methylsilane molecules in the supersonic jet, the growth temperature was as low as 670 degreesC. The reduction of the growth temperature is explained in terms of a decrease in the activation energy and enhancement of the reaction efficiency from methylsilane to the SiC film during film growth. More importantly, a high growth rate of SiC at low temperature yielded submicron patterns of SiC without degradation of the SiO2 mask.X117sciescopu
Photoluminescent properties of ZnO thin films grown on SiO2/Si(100) by metal-organic chemical vapor deposition
No full textWe report on the photoluminescent (PL) properties of ZnO thin films grown on SiO2/Si(100) substrates using low pressure metal-organic chemical vapor deposition. The growth temperature of the films was as low as 400 degreesC. From the PL spectra of the films at 10-300 K, strong PL peaks due to fi-ee and bound excitons were observed. The origin of the near bandedge emission peaks was investigated measuring temperature-dependent PL spectra. In addition, the ZnO films demonstrated a stimulated emission peak at room temperature. Upon illumination with an excitation density of 1 MW/cm(2), a strong, sharp peak was observed at 3.181 eV.X1146sciescopu
Near ultraviolet light emitting diode composed of n-GaN/ZnO coaxial nanorod heterostructures on a p-GaN layer
Full text linkThe authors report on the fabrication and characteristics of near ultraviolet nanorod light emitting diodes (LEDs) composed of n-GaN/ZnO nanorod heterostructures on p-GaN substrates. The nanorod LEDs consist of the vertically aligned n-GaN/ZnO coaxial nanorod arrays grown on a p-GaN substrate. The LEDs demonstrated strong near ultraviolet emission at room temperature. The nanorod LEDs were turned on a forward-bias voltage of 5 V, and exhibited a large light emitting area. From electroluminescent spectra, dominant emission peaks were observed at 2.96 and 3.24 eV for an applied current of 2 mA. The origins of the strong and large area light emission are also discussed in terms of enhanced carrier injection from n-GaN nanostructures to p-GaN substrates.open114148sciescopu
Photoluminescent properties of Se-doped GaN
No full textThe nature of Se donors in GaN was investigated using temperature dependent photoluminescence spectroscopy. Near-bandedge emission of the doped films was investigated at temperatures between 15-300 K. Based on the temperature dependence of the near-bandedge emission, the Se donor level in GaN was estimated to be 38 +/- 4 meV below the conduction band minimum.X111sciescopu
Electrical and optical characteristics of hydrogen-plasma treated ZnO nanoneedles
Full text linkWe report on optical characteristics as well as electron emission of hydrogen-plasma treated ZnO nanoneedle arrays. The nanoneedle arrays were vertically grown on Si substrates using catalyst-free metalorganic chemical vapor deposition and subsequently treated by hydrogen plasma at room temperature. After hydrogen plasma treatment, the field emission characteristic curves of nanoneedle arrays exhibited significantly reduced turn-on field and increased emission current density, and the electrical conductivity was increased. In addition, low temperature photoluminesence (PL) measurements indicate that a neutral-donor bound exciton PL peak intensity was increased by the hydrogen- plasma treatment. These effects of the plasma treatment on the physical properties may be explained in terms of hydrogen doping effect. (c) 2005 American Vacuum Society.open112224sciescopu
Probing exciton diffusion in semiconductors using semiconductor-nanorod quantum structures
No full textX1120sciescopu
Fabrication and photoluminescent characteristics of ZnO/Mg0.2Zn0.8O coaxial nanorod single quantum well structures
Full text linkThe authors report on fabrication and photoluminescent (PL) properties of ZnO/Mg0.2Zn0.8O coaxial nanorod quantum structures with various quantum well and barrier layer thicknesses. Employing catalyst-free metal-organic vapor-phase epitaxy, coaxial nanorod single quantum well structures were fabricated by the alternate heteroepitaxial growth of ZnO and Mg0.2Zn0.8O layers over the entire surfaces of the ZnO nanorods with fine thickness controls of the layers. The quantum confinement effect of carriers in coaxial nanorod quantum structures depends on the Mg0.2Zn0.8O quantum barrier layer thickness as well as the thickness of the ZnO quantum well layer. The temperature-dependent PL characteristics of the coaxial nanorod quantum structures are also discussed. (c) 2006 American Institute of Physics.open113638sciescopu
ZnO nanorods: synthesis, characterization and applications
No full textThis paper presents a review of current research activities on ZnO nanorods (or nanowires). We begin this paper with a variety of physical and chemical methods that have been used to synthesize ZnO nanorods (or nanowires). There follows a discussion of techniques for fabricating aligned arrays, heterostructures and doping of ZnO nanorods. At the end of this paper, we discuss a wide range of interesting properties such as luminescence, field emission, gas sensing and electron transport, associated with ZnO nanorods, as well as various intriguing applications. We conclude with personal remarks on the outlook for research on ZnO nanorods.X11529sciescopu
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