Four Birds with One Stone”: Synthesis of Nanostructures of ZnTe, Te, ZnAl2O4, and Te/ZnAl2O4 from a Single-Source Precursor (original) (raw)
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Journal of Materials Science: Materials in Electronics, 2012
ZnCuTe nanowires have been successfully synthesized via template-assisted one step electrodeposition technique from an aqueous solution of zinc sulphate (ZnSO 4 Á7H 2 O), copper sulphate (CuSO 4 Á5H 2 O) and tellurium oxide (TeO 2) at room temperature (303 K). Nanowires of diameter 200, 100 and 50 nm have been synthesized on copper and indium tin oxide coated glass substrates using track-etch polycarbonate membranes (Whatman). The morphologies and structures of electrodeposited ZnCuTe nanowires were characterized by Scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM confirmed the formation of nanowires and reveal that the morphologies of nanowires have diameter equal to the diameter of the templates used. The XRD pattern have shown a preferential growth of ZnCuTe nanowires along the (119) direction and the structure corresponding to hexagonal structure. Energy dispersive X-ray analysis confirmed that the zinc copper telluride nanowires are constituted of elements Zn, Cu and Te.
Optical properties of single ZnTe nanowires grown at low temperature
Applied Physics Letters, 2013
Optically active gold-catalyzed ZnTe nanowires have been grown by molecular beam epitaxy, on a ZnTe(111) buffer layer, at low temperature (350 • C) under Te rich conditions, and at ultra-low density (from 1 to 5 nanowires per µm 2 ). The crystalline structure is zinc blende as identified by transmission electron microscopy. All nanowires are tapered and the majority of them are 111 oriented. Low temperature microphotoluminescence and cathodoluminescence experiments have been performed on single nanowires. We observe a narrow emission line with a blue-shift of 2 or 3 meV with respect to the exciton energy in bulk ZnTe. This shift is attributed to the strain induced by a 5 nm-thick oxide layer covering the nanowires, and this assumption is supported by a quantitative estimation of the strain in the nanowires.
MBE Growth and Properties of ZnTe- and CdTe-Based Nanowires
Journal of the Korean Physical Society, 2008
We review our results on the growth of ZnTe-and CdTe-based nanowires (NWs) and on their basic structural and optical properties. The nanowires were produced by using molecular beam epitaxy (MBE) with the use of a mechanism of catalytically-enhanced growth. The growth of ZnTe, CdTe, ZnMgTe and ZnMnTe nanowires was performed from elemental Zn, Cd, Mn, Mg and Te sources on the surfaces of (001)-, (110)-and (111)B-oriented GaAs substrates with Au nanocatalysts. The morphological and structural properties of the nanowires were assessed by using X-ray diffractometry, field-emission scanning electron microscopy, and high resolution transmission electron microscopy. Additional studies of the compositions of both the nanowires and the Au-rich nanocatalysts were performed with the use of energy dispersive X-ray spectroscopy. The optical properties of the NWs were assessed by using photoluminescence and Raman-scattering studies performed in both macro and micro modes. The studies revealed that binary and quaternary nanowires with average diameters from 30 to 70 nm and lengths from 1 to 2.6 µm were monocrystalline in their upper parts, their growth axis was 111 , and they grow along the [111] direction of the substrate, independent of the substrate orientation used. A Au-rich (with 20 % Ga) spherical nanocatalyst was always visible at the tip of a nanowire, thus indicating that a vapor-liquid-solid mechanism was responsible for the growth of the ZnTe-and the CdTe-based nanowires. The formation of homogeneous mixed crystal ZnMnTe and ZnMgTe nanowires was demonstrated by measurements of the variation of the lattice constant and by Raman experiments that revealed the expected shift and appearance of new phonon lines and a strong enhancement of the LO-phonon structures for an excitation close to the exciton energy of the NW materials. The photoluminescence from the internal Mn 2+ transition between crystal-field-split energy levels (4 T1 → 6 A1) was observed in the ZnMnTe nanowires.
Synthesis and Characterization of Metal and Semiconductor Nanowires
One-dimensional nanowires (NWs) have attracted considerable attention in recent years because of their novel physical properties and potential applications as interconnects in nanometre-scale electronics. NWs have potential applications in nanoscale electronics, optoelectronics, photonics, sensors, and solar cells due to their unique electrical, chemical, and optical properties. Several chemical and physical methods are commonly used to produce NWs. Among them, electrochemical synthesis and vapour-liquid-solid (VLS) methods to produce NWs have become popular among scientific workers due to a number of advantages. Synthesis of NWs using anodic alumina and polymer templates in an electrochemical cell has been described in detail as investigated in our laboratory. Characterization of metal and semiconductor NWs has been accomplished using scanning electron microscope (SEM), field emission scanning electron microscope (FESEM), high resolution transmission microscope (HRTEM), X-ray diffraction (XRD), and energy dispersive X-ray analysis (EDAX). Morphology of NWs has been revealed by SEM, structure by TEM, crystallinity by XRD and chemical composition by EDAX. I-V characteristics of copper and semiconductor NWs were recorded in-situ, as grown in pores of anodic alumina template, using Dual Source Meter (Keithley Model 4200 SCS) with platinum probes for contacts. Resonating tunneling diode (RTD) characteristics of fabricated NWs have been investigated. Bulk production of Copper NWs has been described by seed growth technique. Applications of NWs are not covered in any detail under this review.
ZINC OXIDE NANOWIRES SYNTHESIZED BY THERMAL EVAPORATION METHOD WITH AND WITHOUT CATALYST
The fabrication of zinc oxide nanowires and their characterization are presented in this paper. Gold catalyst was employed on certain set of experiments. The sample were fabricated within a horizontal quartz tube under controlled supply of O2 and Ar gases and heated at 700 o C up to 1200 o C. Initially, the tube was evacuated around 1 torr using a mechanical pump and the gas is allowed to pass at a known flow rate so that the evaporated source will be driven to the Silicon substrate. The substrate was previously cleaned and deposited with gold nanoparticles using a dipping process to act as a catalyst during vapor-liquid-solid mechanism. Another set of samples was prepared without the aid of gold catalyst and the process involved is called selfcatalytic growth. The structural morphology of both catalyst and catalyst-free samples was characterized using scanning electron microscopy and field emission scanning electron microscopy, whilst the field emission properties of the nanowires were measured using photoluminescence spectroscopy at room temperature. Both SEM and FESEM results showed that the optimal conditions for the growth of ZnO nanowires with gold catalyst were identified as follows: 90 mins growth time and gas flow rate ranging from 1.1 to 5.0 sccm. High aspect ratio of around 10.5 and low surface density were also observed. Catalyst-free ZnO:Al nanowires showed a randomly orientated nanowires with varying nanostructures as the dopant concentrations were increased from 0 to 2.4 at%. Interesting features were observed at 2.4 at%, shown by a perfect hexagonal similar to 'pencil-like' shape. This was further analysed by EDX which confirmed an optimal level of dopant concentration for the synthesis of ZnO:Al nanorods. The measured diameters were roughly between 260 to 350 nm and the length about 720 nm. From The results showed the importance of Al doping that played an important role on the morphology of ZnO nanostructures. This may led to potential applications in sensor and biological applications.
Structure and electrical properties of p-type twin ZnTe nanowires
Applied Physics A, 2011
Resonant tunneling is firstly found in twin ptype ZnTe nanowire field-effect transistors. The twin ZnTe nanowires are synthesized via the thermal evaporation process. X-ray diffraction and high-resolution transmission electron microscopy characterization indicate that the asgrown twin nanowire has a zinc-blende crystal structure with an integrated growth direction of [11-1]. The twin plane is (11-1) and the angle between the mirror symmetrical planes is 141°. The formation of twins is attributed to the surface tension from the eutectic liquid droplet. Field-effect transistors based on single ZnTe twin nanowire are constructed, the corresponding electrical measurements demonstrate that the twin nanowires have a p-type conductivity with a mobility (μ h) of 0.11 cm 2 V −1 S −1 , and a carrier concentration (n h) of 1.1 × 10 17 cm −3. Significantly, the negative differential resistance with a peak-to-valley current ratio of about 1.3 is observed in p-type twin ZnTe nanowire field-effect transistors at room temperature. As the periodic barriers produced in the periodic twin interfaces can form
Korean Journal of Chemical Engineering, 2006
Synthesis of ZnO nanowires was achieved on Si(100) substrate by the thermal evaporation of high purity metallic zinc powder without the use of any metal catalyst or additives. The diameter and length of the as-grown nanowires were in the range of 20–35 nm and few micrometers, respectively. The shapes and sizes of ZnO nanowires were dependent on the growth time. The high resolution transmission electron microscopy and selected area electron diffraction patterns indicated that the as-grown products are single crystalline with wurtzite hexagonal phase. Room temperature photoluminescence studies exhibited a strong UV emission and a suppressed green emission, confirming the good optical properties for the deposited nanowires.
Synthesis and Photoluminescence Studies on Zinc Oxide Nanowires
ASEAN Journal on Science and Technology for Development, 2017
Semiconductor single crystal ZnO nanowires have been successfully synthesized by a simple method based on thermal evaporation of ZnO powders mixed with graphite. Metallic catalysts, carrying gases, and vacuum conditions are not necessary. The x-ray diffraction (XRD) analysis shows that the ZnO nanowires are highly crystallized and have a typical wurtzite hexagonal structure with lattice constants a = 0.3246 nm and c = 0.5203 nm. The scanning electron microscopy (SEM) images of nanowires indicate that diameters of the ZnO nanowires normally range from 100 to 300 nm and their lengths are several tens of micrometers. Photoluminescence (PL) and photoluminescence excitation (PLE) spectra of the nanowires were measured in the range of temperature from 15 K to the room temperature. Photoluminescence spectra at low temperatures exhibit a group of ultraviolet (UV) narrow peaks in the region 368 nm ~ 390 nm, and a blue-green very broad peak at 500 nm. Origin of the emission lines in PL spectr...