Photocurrent Polarization Anisotropy of Randomly Oriented Nanowire Networks

详细信息    查看全文

• 作者：Yanghai Yu ; Vladimir Protasenko ; Debdeep Jena ; Huili (Grace) Xing ; Masaru Kuno
• 刊名：Nano Letters
• 出版年：2008
• 出版时间：May 2008
• 年：2008
• 卷：8
• 期：5
• 页码：1352 - 1357
• 全文大小：1174K
• 年卷期：v.8,no.5(May 2008)
• ISSN：1530-6992

文摘

While the polarization sensitivity of single or aligned NW ensembles is well-known, this article reports on the existence of residual photocurrent polarization sensitivities in random NW networks. In these studies, CdSe and CdTe NWs were deposited onto glass substrates and contacted with Au electrodes separated by 30–110 µm gaps. SEM and AFM images of resulting devices show isotropically distributed NWs between the electrodes. Complementary high resolution TEM micrographs reveal component NWs to be highly crystalline with diameters between 10 and 20 nm and with lengths ranging from 1 to 10 µm. When illuminated with visible (linearly polarized) light, such random NW networks exhibit significant photocurrent anisotropies ρ = 0.25 (σ = 0.04) [ρ = 0.22 (σ = 0.04)] for CdSe (CdTe) NWs. Corresponding bandwidth measurements yield device polarization sensitivities up to 100 Hz. Additional studies have investigated the effects of varying the electrode potential, gap width, and spatial excitation profile. These experiments suggest electrode orientation as the determining factor behind the polarization sensitivity of NW devices. A simple geometric model has been developed to qualitatively explain the phenomenon. The main conclusion from these studies, however, is that polarization sensitive devices can be made from random NW networks without the need to align component wires.