砷化镓纳米线晶相控制和电子性质的理论研究

Controlling the crystal quality and electronic properties of GaAs nanowires is a key technology for their applications in the optoelectronic devices. However, GaAs nanowires often exhibit a high density of randomly distributed stacking faults and twin defects during the growth, which results in the uncontrolled crystal phase and electronic properties and limits the applications of GaAs nanowires in the nano-devices. We propose to study the two-dimensional nucelation system and electronic structure of GaAs nanowires by combining the full quantum first-principles calculations and two-dimension nucleation dynamics in order to realize the control of crystal phase of nanowires and electronic properties. The comparison of nucleation difference between GaAs nanowires in the zinc-blende and wurtizite phases is used to understand the formation mechanism of crystal defects, a theoretical scheme for the crystal phase control of nanowires is obtained by investigating the effects of chemical potential and the supersaturation of Au catalyst on the crystal phase formation of nanowires, and the relationship between the crystal phase of nanowires and their electronic structures is established. The research results will greatly enhance our knowledge on the growth mechanism of III-V semiconductor nanowires and provide theoretical basis and guidance for the experimental realization in controlling the crystal phase and electronic properties of GaAs nanowires.

控制砷化镓纳米线的晶体质量和电子性质是实现其在光电子器件上应用的关键技术之一。然而，砷化镓纳米线生长过程中经常产生大量随机分布的层错和孪晶缺陷导致其晶相和电子性质并不容易控制，极大地制约了它们在纳米器件上的应用。本项目拟结合全量子的第一性原理计算和二维成核动力学模型以砷化镓纳米线的二维成核系统和电子结构为研究对象，以实现纳米线晶相和电子性质的调控为目标。通过比较砷化镓纳米线的闪锌矿和纤锌矿相的成核差异，获得晶体缺陷形成机制; 调查化学势和金催化剂过饱和度对纳米线晶相形成的影响，找到控制纳米线晶相的理论方案，并建立纳米线晶相和电子结构的相关性。研究成果将加深对III-V族半导体纳米线生长机理的认识，并为实验上实现砷化镓纳米线晶相和电子性质的调控提供理论基础和指导。

控制砷化镓纳米线的晶体质量和电子性质是实现其在光电子器件领域应用的关键技术之一。本项目采用全量子的第一性原理计算方法与经典成核理论相结合探索砷化镓基纳米线的可控生长机理及其电子结构特征，获得主要成果如下：1) 构建了适用于金催化砷化镓基纳米线生长的二维成核动力学模型，从成核动力学的角度解释了为何纳米线生长过程中容易形成层错和孪晶缺陷，并揭示了砷化镓基纳米线晶相和形貌可以通过表面能和化学势调控的微观机制；2) 建立了砷化镓和磷化铟纳米线结构和电子性质与纳米线尺寸、晶面和晶相的定量依赖关系，解释了实验上关于这些纳米线带隙上的争议；3) 拓展了本项目的研究方法和研究思路，并利用这些研究思路揭示了化学势调节单层二硫化钼(MoS2)纳米材料形貌、电子和磁性性质的热力学机制。通过本项目的研究，为实验上实现砷化镓纳米线及其它纳米材料的晶相、形貌和电子性质的控制提供了理论依据和研究基础。