The effect of growth duration on the morphology and optical properties of NRAs has been investigated. Methods AZO films were Selleck MK-0518 deposited on quartz substrates using a radio-frequency (RF) magnetron sputtering system at room temperature. The quartz substrates, 0.5 mm thick, 2.5 cm × 2.5 cm, were cleaned in acetone and ethanol several times before deposition. The target, 60-mm diameter, was a commercial ZnO and Al2O3 mixture (97:3 wt.%) of ≥99.99% purity. The sputtering was performed in an Ar atmosphere with a target-to-substrate distance of 5 cm. The base pressure

in the chamber was 4.0 × 10−4 Pa. The Ar flux determined using a mass flow-controlled regulator was maintained at 50.0 sccm, and the sputtering JPH203 pressure was 0.5 Pa. The RF power was 300 W, and deposition time was typically Combretastatin A4 10 min. A typical sheet resistance of AZO film, about 480 nm thick, was about 60 Ω/sq. ZnO NRAs were grown by a vapor-phase method in a horizontal tube furnace [18]. The substrates, polycrystalline AZO films on quartz substrates, were cleaned in acetone and ethanol before the NRA growth. Commercial zinc (99.99% purity) powder in a ceramic boat was used as the zinc vapor source. The ceramic boat and AZO substrate were placed in a long quartz tube, and the quartz tube was then put into the furnace. An AZO substrate was placed 5 cm downstream from the sources at the heat center of the furnace. After evacuating the system to a

base pressure of 12 Pa, the furnace temperature was ramped to 600°C at 20°C min−1. A 100-sccm Ar and 10-sccm oxygen mixed gas was introduced into the furnace only when the maximum temperature was reached. The growth pressure was 110 Pa. The temperature was kept at 600°C for several minutes, and then the furnace was cooled down to room temperature. Changing the growth duration, several samples had been synthesized. For simplicity, the samples with growth durations of 3, 6, 8, 9, and 12 min were defined as samples S1, S2, S3, S4, and S5, respectively.

Morphological ZD1839 and structural properties of the grown nanostructures were analyzed using a JSM-7500LV scanning electron microscope (SEM) and a JEM-2010 high-resolution transmission electron microscope (TEM) (JEOL Ltd., Akishima-shi, Japan). For the latter, the samples were prepared by mechanically scraping NRs from the substrate, dispersing them in ethanol, and depositing a drop of the dispersion on a circular copper grid covered by a thin holey carbon film. The crystal structure and orientation were investigated using an X-ray diffractometer (XRD; Y-2000, Rigaku Corporation, Shibuya-ku, Japan) with monochromated Cu Kα irradiation (λ = 1.5418 Å). The surface morphology of the AZO film was observed using an atomic force microscope (AFM; CSPM 4000, Benyuan Co. Ltd., Guandong, China) under ambient conditions. The sheet resistance was measured by the van der Pauw method [19].