Designing the Electronic Properties of PbSe Nanowires for Optoelectronic Devices

技术描述：半导体纳米线允许对一维材料中出现的独特材料的物理特性进行研究，并为广泛的应用开发其特性。PbSe是一种独特的一维探测材料体系：它具有大的电子、空穴和激子玻尔半径，在小直径的纳米线中产生强烈的量子限制，并且与基质相比具有更大的介电常数，导致强烈的介电限制。纳米线中的限制效应极大地改变了它们的电子结构以及载流子统计、动力学和输运。这个项目的目的是了解强量子和介电限制对PbSe纳米线电子性质的影响，以及它们在设计纳米线p-n结，特别是中红外光电探测器和光伏方面的重要性。合成了直径在4~20 nm之间可调的胶体PbSe纳米线，并将其作为单根纳米线和纳米线阵列集成在嵌入不同介电环境的器件中。在纳米线集成之后，替代和远程掺杂纳米线的路线被用于了解这些一维、强量子和介电受限半导体中的掺杂及其效率，并可控制地定义高迁移率纳米线中的p-n结。电学和光电子测量用于探测n和p掺杂PbSe构建块中的掺杂效率和电荷注入和传输，以及p-n结的静电学、载流子扩散和性能，以设计高效率的光电子器件。非技术描述：半导体器件是通过定义n和p型掺杂区之间的结来构造的，分别引入多余的电子和空穴。在一维材料中，p-n结受到其小直径以及纳米线与其周围材料的介电常数之间的反差的影响。这个项目探索了半导体材料中一维的影响，在那里，小尺寸和介电对比度的影响很高。这些纳米线有望用于高效率的中红外光电探测器和光伏发电。该项目为本科生和研究生提供跨学科的研究经验。PI和学生通过学生课程和外联活动分享一维纳米材料的科学和技术，以吸引K-12学生、教师和普通公众的参与。

Technical Description: Semiconductor nanowires allow the interrogation of unique materials physics that arises in one-dimensional materials and the exploitation of their properties for a wide range of applications. PbSe is a unique materials system to probe in one-dimension: it has large electron, hole, and exciton Bohr radii, giving rise to strong quantum confinement in small-diameter nanowires, and it has a large dielectric constant compared to host matrices, leading to strong dielectric confinement. Confinement effects in nanowires dramatically alter their electronic structure as well as carrier statistics, dynamics, and transport. The goal of this project is to understand the influences of strong quantum and dielectric confinement on the electronic properties of PbSe nanowires and their importance in designing nanowire p-n junctions in particular for mid-infrared photodetectors and for photovoltaics. Colloidal PbSe nanowires, tunable from 4 to 20 nm in diameter, are synthesized and integrated as single nanowires and nanowire arrays in devices embedded in different dielectric environments. After nanowire integration, routes to substitutionally and remotely dope nanowires are applied to understand doping and its efficiency in these one-dimensional, strongly quantum and dielectrically confined semiconductors and to controllably define p-n junctions within high-mobility nanowires. Electrical and optoelectronic measurements are used to probe doping efficiency and charge injection and transport in n- and p-doped PbSe building blocks and the electrostatics, carrier diffusion, and performance of p-n junctions to design high-efficiency optoelectronic devices.Non-technical Description: Semiconductor devices are constructed by defining junctions between n- and p-type doped regions, to introduce excess electrons and holes, respectively. In one-dimensional materials, the p-n junctions are affected by their small diameter as well as by contrast between the dielectric constant of the nanowires and their surrounding materials. This project explores the impact of one dimension in a semiconductor material where the effects of small size and dielectric contrast are high. These nanowires are promising for high-efficiency mid-infrared photodetectors and for photovoltaics. This project provides an interdisciplinary research experience for undergraduate and graduate students. The PI and students are sharing the science of one-dimensional, nanoscale materials and their technologies through student coursework and outreach activities to engage K-12 students, teachers, and the general public.