宽带隙氮/氧化物广义掺杂规则及对载流子特性的调控研究

Using first-principles calculations based on density functional theory，we study the general rule to select doping sites for nitrides/oxides and their tunable carriers properties. First, we study the selection rule of typical doping sites for binary and ternary n-type nitrides/oxides, selection rule of rare earth and transition metal and compensation anion and cation pairs, as well as the effect of strain and quantum confinement on such doping rule and conditions. Based on the former investigations, we further study how do the doping rule and conditions affect the carriers properties，especially on electricity properties: these investigations mainly focus on the band edge properties changing trend of condition band and valence band of nitrides/oxides, what role of different donor and acceptor states plays in the band gap or edges, especially the role of surfactant, and the effect of variable defects and impurities on the photo electricity properties at equilibrium growth conditions. Then we will give an optimized rule to improve the photo electricity properties for nitrides/oxides. At last, we investigate on the p-n junction properties comprised with nitrides and oxides as well as single layer semiconductor, including BN sheet, graphyne, and silicene. Also, we probe into the band offset between different materials and understand how does band offset effect on the photo electricity properties. This project will guide how to tune photo electricity properties of nitrides/oxides in experiment and further improve the development of the functionalized devices.

本课题利用第一性原理计算方法研究氮/氧化物半导体广义的掺杂规则及其对载流子特性的影响。首先研究二元和三元氮/氧化物掺杂点位置选择规则，稀土和过渡金属原子掺杂选择规则，阴阳离子对补偿掺杂选择规则及它们在应力和量子限域效应下的变化特征，给出广义的掺杂规则。在此基础上进一步研究上述规则和条件对氮/氧化物载流子特性的调控与改良：主要表现在氮/氧化物的价带和导带带边附近电子结构的变化规律，带隙中施受主杂质态的变化规律及所扮演的稳定角色（表面活性剂角色和氢原子），平衡生长条件下不同掺杂和缺陷对载流子特性的影响，给出调控氮/氧化物光电特性的优化方案。最后研究氮氧化物之间形成异质结及它们与单层半导体形成p-n节，包括硼氮片，石墨烯/炔，硅烯等，探讨不同带阶，组分比例和应力对光电性能的影响，本课题将对实验上通过掺杂调控氮/氧化物材料的光电性能提供理论指导，促进功能化器件的研究开发。

缺陷或掺杂，裁剪、化学修饰、应变、电场等作为有效调控材料电子和磁性特征的有效手段，包括传统的宽带隙氮/氧化物，二维和一维半导体纳米材料。本项目基于密度泛函理论的第一性原理方法结合紧束缚近似和wannier函数：.（1）重点研究了空位和缺陷原子（分子）掺杂对Ⅳ,Ⅴ族基低维半导体纳米材料g-CN纳米片，磷烯等电子，磁性和稳定性调控，包括3d电子在晶体场中的劈裂和自旋极化，非金属掺杂原子在半导体中的缺陷态特征；共掺杂提高VBM进而增强p型ZnO纳米带；N2分子掺杂的GaAs产生自旋极化；还研究了Sb掺杂As烯提高VBM进而减少电场强度来实现与石墨烯堆垛后由肖特基接触到p-n节的相变。（2）接下来研究了化学修饰，应变对Ⅳ,Ⅴ族基g-CN纳米带，磷烯纳米片/带的电子，磁性和稳定性调控，发现这些方法可以诱导本征的自旋极化，费米能及附近完全由单一自旋态决定，铁磁反铁磁存在竞争，铁磁到非磁存在相变。（3）最后研究了磁性氧化物衬底效应对拓扑绝缘体Mxene带隙和边缘态的调控。与课题组成员合作还研究了贵金属原子对分子的催化，合金衬底效应调控石墨烯纳米片的生长，电场调控两层石墨烯纳米片的摩擦特征。..通过此项目三年的资助研究，取得了一定的积极成果，达到了一定的研究目的。.项目执行期间在SCI期刊上共发表论文11篇，正在整理的有五篇。协助培养博士生五名，毕业2人，在读3名，硕士研究生3名，毕业3名。