A 30 渭m Coaxial Nanowire Photoconductor Enabling Orthogonal Carrier Collection
详细信息 查看全文
- 作者：Qiang Xu ; Shaopeng Qiao ; Rajen Dutta ; Mya Le Thai ; Xiaowei Li ; Crystin J. Eggers ; Girija Thesma Chandran ; Zhengyun Wu ; Reginald M. Penner
- 刊名：Nano Letters
- 出版年：2015
- 出版时间：September 9, 2015
- 年：2015
- 卷：15
- 期：9
- 页码：5861-5867
- 全文大小：478K
- ISSN：1530-6992
文摘
We describe the preparation and properties of a coaxial, three-layer, gold-CdSe-gold nanowire 30 渭m in length that functions as a monolithic photodetector. The gold (Au) electrode core of this sandwich structure is prepared using the lithographically patterned nanowire electrodeposition (LPNE) method on a glass surface. A CdSe shell of defined thickness, dCdSe, from 200 to 280 nm is then electrodeposited on this Au nanowire. Finally, a conformal gold layer is electrodeposited on top of the CdSe shell. The two concentric gold electrodes within this architecture measure the photoconductivity of the ultrathin CdSe absorbing layer in the direction orthogonal to the nanowire axis. This architecture enables accelerated response/recovery of the nanowire to light while simultaneously maximizing the photoconductive gain without relinquishing any of the photoresponsive area of a 鈥漛are鈥?nanowire. Characterization by scanning electron microscopy (SEM) of focused ion beam (FIB) cross sections together with electron dispersive X-ray spectroscopy (EDS) reveal the distinct core鈥搈ultishell nanostructure, layer thicknesses, and layer compositions. The position-dependent photoresponse along the axis of the nanowire, probed using a laser spot, shows that the Au nanoshell significantly enhances the photocurrent. The performance of Au鈥揅dSe鈥揂u core鈥搈ultishell nanowire photodetectors depend sensitively on the thickness of CdSe nanoshell over the range of from 200 nm < dCdSe < 280 nm. The highest performance was obtained for the dCdSe = 250 nm this device, which showed a photoconductive gain of 2172, a responsivity of 209 A路W鈥?, a response time of 17 渭s, and a recovery time of 96 渭s.