AlN晶体的高效P型掺杂

Aluminum nitride (AlN) is a kind of wide bandgap semiconductor materials. It has very good application prospect in ultraviolet-photoelectronic and high temperature, high power electronic devices, etc. However, in order to realize the application of AlN, it is essential to achieve a good n-type and p-type doping. N-type AlN can be achieved by doping silicon (Si), but p-type AlN still is a worldwide problem. In this project, we will explore Mg-O, Be-O, and C-Si, etc., codoped AlN by using physical vapor phase transport (PVT) method. Through the donor-acceptor co-doping to improve the concentration of acceptor atoms, and to shallow the acceptor level and donor level at the same time, efficient p-type doping will be realized. And the hole concentration will meet the need of devices. We will combine the theory with experiments and establish supercells of doped AlN through first-principles calculation based on density functional theory (DFT), for finding out the optimal doping combination and ratio and in return guiding the experiments. Furthermore, we will take full advantage of the experience acquired through growing and doping AlN with our self-developed crystal growth equipment to obtain AlN single crystals with higher purity and fewer defects, and investigate their structural and physical properties, so that to enhance the p-type doping efficiency and hole concentration gradually.

氮化铝（AlN）是一种宽带隙半导体材料，在紫外光电子和高温、高功率电子器件等方面具有很好的应用前景。但是AlN能够应用的前提是实现良好的n型和p型掺杂。n型AlN可以通过硅(Si)掺杂实现，而p型AlN却依然是个世界性难题。本项目将利用物理气相传输(PVT)法进行Be-O、Mg-O、C-Si等共掺杂AlN生长研究，通过施主-受主共掺杂来提高受主原子的掺入量，并使受主能级与施主能级同时浅化，实现高效p型AlN掺杂，使空穴浓度达到器件需要的水平。我们将采用理论和实验相结合的方法，利用基于密度泛函理论(DFT)框架下的第一性原理计算方法，建立掺杂AlN的超晶胞体系进行模拟，力求分析找出最优掺杂组合及配比，指导实验计划，并充分利用自主研发的晶体生长设备和长期以来在PVT法生长AlN晶体和掺杂AlN方面积累的经验，生长出纯度高、缺陷少的共掺杂AlN单晶，对其进行结构和物性表征，逐步提高p型掺杂效率。

AlN作为一种典型的直接宽禁带半导体材料，在深紫外电子器件方面有广泛的应用前景。pn结是半导体器件的核心结构，高质量AlN同质pn结对实现其高效的性能极其重要。然而，由于宽禁带半导体普遍存在掺杂不对称的问题，很难获得高质量的p型。在本项目的支持下，我们通过理论计算和实验相结合的方法，对AlN晶体p型掺杂和单晶生长及物性开展了研究工作，取得如下创新成果：（1）利用第一性原理计算方法，从理论上发现Be-O共掺杂可实现AlN高效p型掺杂。（2）突破了AlN单晶生长关键技术，开发出扩径生长工艺，获得了直径约2cm的AlN晶片。（3）首次测得了AlN的双光子吸收系数和非线性折射率，为AlN在非线性光学性质方面积累了基础数据。（4）在Fe掺杂的AlN多晶样品中室温下观察到铁磁性，表明Fe掺杂AlN晶体有望用于自旋电子器件。