Photoconductive Metal Nanowires with Embedded Semiconductor Nanonodes

技术说明：一种新的策略正在研究中，用于创建纳米级光电导体，其在光电导状态对光的响应和恢复（100 ns）方面都是快速的，并且对光高度敏感，具有高的内部光电导增益（100）。增益，定义为每个吸收光子产生的电子数量，可以通过在长度上折叠半导体纳米线直到它成为半导体纳米颗粒，在一对金属电触点之间进行支撑来最大化。这种布置是通过制备交叉纳米线阵列来实现的，其中例如，硒化镉的双波长（100 nm）光吸收层夹在两个金纳米线之间。使用相同的交叉纳米线策略获得发光结或纳米节点，不同之处在于一组金属纳米线被p型半导体纳米线（例如银（I）氧化物或PEDOT（聚（3，4-亚乙基-二氧噻吩）代替。由此形成光电发射n-p结。用于制备用作光电导光学传感器和光电发射结的交叉纳米线结的密集阵列的方法正在开发中。这些结构的基本方面正在探讨使用单交叉纳米线结。光电导阵列用于检测空间调制光源的属性，以及光电发射阵列用于产生空间调制光的集体属性将被表征。非技术描述：目前正在研究一种新的方法，用于制造小于光波长的光学探测器和光源。在这个项目中，由金属或半导体组成的纳米线的线性阵列被叠加在彼此的顶部，以创建纳米线交叉或结的阵列。这种交叉的纳米线策略应该能够产生数百万个光学探测器或光源的阵列。该项目为研究生提供了多学科的培训经验，包括纳米纤维，表面化学，电化学，凝聚态物理和光谱学。在开展这些研究活动的同时，还开展了一项以经济困难的高中生为对象的奖学金外联方案。

Technical Description: A new strategy is under investigation for the creation of nanometer-scale photoconductors that are both fast, in terms of the response and recovery of the photoconductive state to light (100 ns), and highly sensitive to light, possessing a high internal photoconductive gain (100). The gain, defined as the number of electrons produced for each absorbed photon, can be maximized by collapsing a semiconductor nanowire in length until it becomes a semiconductor nanoparticle, cradled between a pair of metal electrical contacts. This arrangement is achieved by preparing arrays of crossed nanowires in which an ultrathin (100 nm) optical absorbing layer of cadmium selenide, for example, is sandwiched between two gold nanowires. Light-emitting junctions or nanonodes are obtained using the same crossed-nanowire strategy except that one set of metal nanowires is replaced by p-type semiconductor nanowires, such as silver (I) oxide or PEDOT (poly (3,4-ethylene-dioxythiophene)). A photoemissive n-p junction is thereby formed. Processes for preparing dense arrays of crossed nanowire junctions that function as photoconductive optical sensors and photoemissive junctions are being developed. Fundamental aspects of these structures are being probed using single crossed nanowire junctions. The properties of photoconductive arrays for detecting spatially modulated light sources, and the collective properties of photoemissive arrays for generating spatially modulated light will be characterized. Non-technical Description: A new method is being studied for fabricating optical detectors and light sources that are smaller than the wavelength of light. In this project, linear arrays of nanowires composed of metal or semiconductors are superimposed on top of one another to create an array of nanowire crossings or junctions. This crossed nanowire strategy should be capable of producing arrays of millions of optical detectors or optical sources. This project provides a multidisciplinary training experience for graduate students that encompassing nanofabrication, surface chemistry, electrochemistry, condensed matter physics, and spectroscopy. A fellowship-based outreach program that targets economically disadvantaged high-school students is operating in parallel with these research activities.