可控III-V族纳米线结构生长机理和特异光电性质研究

The III-V semiconductor nanomaterials have great potential applications in the field of optoelectronics. The growth of high-quality nanowires with special structures and good physical properties has been the focus of the international researches. Although some advancements have been achieved, the growth model and its control mechanisms of electronic states are far from perfect and many challenges are still remaining to be explored. This project proposes to study the key challenges in this field including the self-assembled growth, the growth mechanisms, and the special optoelectronic properties of III-V semiconductor nanowires by combining the experimental and theoretical approaches. In order to achieve these goals and establish a solid base for exploring the application of III-V semiconductor nanowires in the field of infrared detectors, this project will focus on the following key problems. We will construct the growth model of GaAs- and InAs-based microstructures of semiconductor nanowires, and explor the growth mechanisms of GaAs- and InAs-based nanowire structures by MBE technology combined with Au catalysis and autocatalysis. Basing on the growth model, we will realize the object of controlling the growth ways of nanowires. We will establish the combined model of the surface passivation and the doping of nanowires to achieve a stable n-type and p-type doping. We will focus on the studies of electronic properties of nanowires with different scales and structures. The results will help to control the characteristics of confined carrier states and the distribution of the energy band structure and the density of states. We will further study the optoelectroni properties of GaAs- and InAs-based nanowire materials. Particularly, the experiments will be performed under the conditions of supporting for the effective coating nanowires, where we will observe the transport properties of single nanowires and core-shell composite structures. The photocurrent response of single nanowires will be obtained with light excitation. Based on the optoelectronic properties, their applications in infrared optoelectronic devices will be discussed. The results obtained through this project thus will help to reveal the growth mechanisms of III-V semiconductor nanowires, and provide solid theoretical bases for their further applications on the infrared detector field.

III-V族半导体纳米线在光电子领域巨大应用潜力，使得实现高质量、特定结构、电子态可控的纳米线成为国际的热点，其动力学生长模型一直争论和电子态的控制机理仍有待探索。本项目采用实验和理论相结合研究III-V族纳米材料制备、生长机理和特异光电性质及其应用，澄清GaAs和InAs基半导体纳米线微结构的生长模型的争论，利用分子束外延技术结合Au催化和自催化探索生长GaAs和InAs基纳米线结构，实现对其生长途径的控制；建立纳米线表面钝化和掺杂结合的模型，实现其稳定的n型和p型掺杂；调节不同尺寸和构型的纳米线电子态特征，实现对载流子流动的限制、能带结构和态密度分布控制；进一步制备单纳米线的红外器件结构，在对其有效包裹支撑条件下，测量单纳米线及核壳复合结构的输运特性，揭示单纳米线的光电流响应与微结构的关系，探讨其在红外光电子器件中的应用，为获得高增益和集成的III-V半导体纳米线红外探测器件提供基础。

III-V族半导体纳米线在光电子领域巨大应用潜力，使得实现高质量、特定结构、电子态可控的纳米线成为国际的热点，其动力学生长模型一直争论和电子态的控制机理仍有待探索。本项目采用实验和第一性原理的理论计算相结合的方式研究一维III-V族半导体纳米材料制备工艺、生长机理、性质表征和特异光电子性质，揭示单纳米线的光电流响应与微结构的关系，探讨其在红外光电子器件中的应用。.利用分子束外延技术结合Au催化和自催化方法生长了高质量的GaAs,InAs基纳米线材料，揭示了GaAs纳米线纤锌矿-闪锌矿结构的相变；通过调节分子束外延生长中V/III比，成功实现无缺陷的纤锌矿结构和闪锌矿结构的InAs纳米线。提出了一种纳米线成核的模型，基于对称性考虑，观测到外延生长的InGaAs纳米线的一种新颖的相分离现象，结合第一性原理计算表明这种现象是由于不同的III族元素与Au催化剂合金化竞争导致InGaAs纳米线相分离。通过构造砷化镓/磷化镓核壳结构能够有效控制表面态对砷化镓纳米线电子性质的影响，结果表明砷反位缺陷的产生会导致纳米线呈现出n型的特征；提出在生长过程中降低砷偏压和通过有效的分子钝化来抑制表面缺陷的作用。实现了基于场效应的InAs纳米线多子探测反常光电响应，光电增益高达-10^5，提高了探测器的灵敏度，实现室温紫外-可见-近红外波段高灵敏光电探测，为实现III-V半导体纳米线获得高增益的红外探测器件的应用建立基础。成功制备单根纳米线光场增强的宽谱快速红外探测器件，通过外光场辅助抑制了背景的载流子浓度，实现了从830nm到3113nm的宽谱探测，器件响应速度提升至几十个µs，探测率高达10^11 Jones；同时，在复合的二维结构中实现成像验证演示。基于纳米线光诱导门效应实现室温下单光子探测；该探测器具有在室温下工作、可分辨光子数、低工作电压、低暗计数率、高探测效率、操作简单、易于制造等特点，同时还能探测偏振信息，为低工作电压的单光子探测提供了新思路。