Tunable Photoconduction Sensitivity and Bandwidth for Lithographically Patterned Nanocrystalline Cadmium Selenide Nanowires

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• 作者：Sheng-Chin Kung ; Wendong Xing ; Wytze E. van der Veer ; Fan Yang ; Keith C. Donavan ; Ming Cheng ; John C. Hemminger ; Reginald M. Penner
• 刊名：ACS Nano
• 出版年：2011
• 出版时间：September 27, 2011
• 年：2011
• 卷：5
• 期：9
• 页码：7627-7639
• 全文大小：1382K
• 年卷期：0
• ISSN：1936-086X

文摘

Nanocrystalline cadmium selenide (nc-CdSe) nanowires were prepared using the lithographically patterned nanowire electrodeposition method. Arrays of 350 linear nc-CdSe nanowires with lateral dimensions of 60 nm (h) × 200 nm (w) were patterned at 5 μm pitch on glass. nc-CdSe nanowires electrodeposited from aqueous solutions at 25 °C had a mean grain diameter, d_ave, of 5 nm. A combination of three methods was used to increase d_ave to 10, 20, and 100 nm: (1) The deposition bath was heated to 75 °C, (2) nanowires were thermally annealed at 300 °C, and (3) nanowires were exposed to methanolic CdCl₂ followed by thermal annealing at 300 °C. The morphology, chemical composition, grain diameter, and photoconductivity of the resulting nanowires were studied as a function of d_ave. As d_ave was increased from 10 to 100 nm, the photoconductivity response of the nanowires was modified in two ways: First, the measured photoconductive gain, G, was elevated from G = 0.017 (d_ave = 5 nm) to ∼4.9 (100 nm), a factor of 290. Second, the photocurrent rise time was increased from 8 μs for d_ave = 10 nm to 8 s for 100 nm, corresponding to a decrease by a factor of 1 million of the photoconduction bandwidth from 44 kHz to 44 mHz.