The growth of Al:ZnO nanorods on a silicon substrate using a low-temperature thermal evaporation method is reported. The samples were fabricated within a horizontal quartz tube under controlled supply of O2 gas where Zn and Al powders were previously mixed and heated at 700°C. This allows the reactant vapors to deposit onto the substrate placed vertically above the source materials. Both the undoped and doped samples were characterized using scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HRTEM) and photoluminescence (PL) measurements. It was observed that randomly oriented nanowires were formed with varying nanostructures as the dopant concentrations were increased from 0.6 at.% to 11.3 at.% with the appearance of 'pencil-like' shape at 2.4 at.%, measuring between 260 to 350 nm and 720 nm in diameter and length, respectively. The HRTEM images revealed nanorods fringes of 0.46 nm wide, an equivalent to the lattice constant of ZnO and correspond to the (0001) fringes with regard to the growth direction. The as-prepared Al:ZnO samples exhibited a strong UV emission band located at approximately 389 nm (E g ?=?3.19 eV) with multiple other low intensity peaks appeared at wavelengths greater than 400 nm contributed by oxygen vacancies. The results showed the importance of Al doping that played an important role on the morphology and optical properties of ZnO nanostructures. This may led to potential nanodevices in sensor and biological applications.

One dimensional metal oxide semiconductor nanowires of copper (I) oxide (Cu2O), zinc oxide (ZnO), and their heterojunction nanowires possess remarkable physical and chemical properties. ZnO and Cu2O are attractive because the metals are abundant on earth, inexpensive, nontoxic. Moreover, these oxides have useful optical and electrical properties suitable for a wide variety of electrical devices, because their electrical conduction can be predictably controlled by doping. We here restrict the disscussion using a Hot Tube Vacuum Thermal Evaporation. The NWs in these devices will be studied by physical vapor deposition known as vapor-liquid-solid (VLS). Therefore, we explore conventional methods, particularly the VLS of growing ZnO and Cu2O nanowires which are assisted by the catalyst. In this short review, we report the individual and combined (Cu2O/ZnO) junction nanowires by PVD method. The main advantages of these composite nanowires are the natural p-n characteristics, the broad light absorption, the high sensitivity to humidity changes, and the fast dynamic response. The combination of all characteristics offered by Cu2O/ZnO nanowires can enable the fabrication of diverse sensing devices, and photovoltaic solar cells.

Cuprous oxide nanowires have been synthesized by heating copper foil in the presence of oxygen rich environment using a hot tube vacuum thermal evaporation method. The effect of growth parameters such as growth time, temperature and oxidative environment on the morphology of the nanowires is investigated. The growth of cuprous oxide nanowires from copper foils thermally oxidized in the presence of oxygen rich at temperatures between 300 and 500 0C. The nanowires were formed within the temperature range of 400 - 500 0C with diameters and length between 25 - 100 nm and length 1 - 4 ?m, respectively. This gave an estimate of aspect ratio around 40. Observation from FESEM results revealed the optimal growth of cuprous oxide nanowires which occurred at oxidation times for 1h, 1/2h and 25 minutes and flow rates of oxygen at 0.09 psi, 0.12 psi and 0.08 psi. The atom% of copper and oxygen were measured using EDX and their existence were later confirmed by XRD, essentially indicated by 40% an 60% of copper and oxygen contents, respectively.

Zinc oxide nanowires have been synthesized using a hot tube vacuum evaporation method. Essentially, ZnO powder and silicon substrate were placed in upper and lower streams of a horizontal quartz tube, respectively and heated via a furnace up to 960 C for about 1 hour. During the heating process, evaporated ZnO vapour was transported to lower stream and deposited onto the substrate containing Au catalyst at constant pressure of 1 torr. The substrate tilt angles were chosen for 0∞ and 30∞ and argon flow rates between 1.1-5.0 sccm. Observation on FESEM/EDX and field emission results revealed the optimal growth of ZnO nanowires which occurred at an angle 30∞ and flow rate of 5 sccm. Parameters such as atom% of Zn and O and aspect ratio were measured and analysed. | Hot-tube thermal evaporation | ZnO Nanowires |Vapour-liquid-solid mechanism