电子结构可调的Zn-IV-N2/ZnO（IV=Ge,Sn）半导体合金及其表面态研究

Zn-IV-N2 is a series of ternary compound semiconductors composed of earth abundant elements. Experiments show that both ZnGeN2 and ZnO are wide-band-gap semiconductors with Eg~3.4 eV, but the band gap of ZnGeN2/ZnO alloy can be lowered to be 2.7 eV. In this proposal, we will theoretically study the microscopic mechanism of the change of electronic structure of Zn-IV-N2/ZnO(IV=Ge,Sn) semiconductor alloys. Research contents are as follows: (1) we will construct the atomic model of ZnGeN2/ZnO alloy and elucidate the physical mechanism of its band gap decrease by analyzing electronic density of states, band structure and wave function; (2) we will theoretically design the ZnSnN2/ZnO new-type alloy suitable for the application in visible light adsorption and study the change of its electronic structure with varying the composition, which will provide theoretical guideline for the experimental synthesis; (3) we will study the surface states of ZnGeN2/ZnO alloy and ZnSnN2/ZnO alloy using the first-principles calculations and tight-binding models, reveal the property and origin of surface states, and elucidate the effect of surface modification on the electronic structure of alloy. Our study will enrich the understanding of the mechanism of electronic structure modulation for semiconductor alloy and has important scientific significance and application value.

Zn-IV-N2是一类由地球上储量比较丰富的元素构成的三元化合物半导体。实验表明ZnGeN2和ZnO都是宽带隙（大约3.4eV）半导体，然而ZnGeN2/ZnO合金的带隙可以降到2.7eV。基于此，本项目将从理论上系统研究Zn-IV-N2/ZnO（IV=Ge,Sn）半导体合金电子结构变化的微观机制。研究内容如下：(1)构造ZnGeN2/ZnO合金的原子模型，通过电子态密度、能带和波函数分析，阐明ZnGeN2/ZnO合金带隙减小的物理机制；(2)理论上设计适用于可见光吸收的ZnSnN2/ZnO新型合金，研究其电子结构随成分变化的规律，为实验制备提供理论指导；(3)结合第一性原理计算和紧束缚模型，研究ZnGeN2/ZnO及ZnSnN2/ZnO合金的表面态，揭示表面态的特征和起源，并阐明表面修饰对合金电子结构的影响。本项目的研究将丰富对合金电子结构调控机理的理解，具有重要的科学意义和应用价值。

具有合适能带特征的半导体系统在光电子领域有着重要的应用价值。Zn-IV-N2半导体是由地球富含的元素所构成，由于其独特的电子性质，引起人们极大的研究兴趣。在本项目中，采用密度泛函理论计算，我们探讨了基于Zn-IV-N2半导体的物质系统的性质。具体内容有：(1)研究了ZnSnN2/ZnO短周期超晶格中内建电场调节的能带结构，发现改变ZnSnN2层和ZnO层的厚度能够有效的调节超晶格的带隙，带隙的变化可以近似用超晶格的结构因子描述；(2)研究了ZnO:ZnSnN2固溶体半导体合金的微观原子特征和能带结构，发现ZnO:ZnSnN2合金具有2.3 eV-2.5 eV的带隙值；(3)研究了GaN、ZnGeN2和ZnSnN2异质结的带阶，发现ZnGeN2/GaN、ZnGeN2/ZnSnN2和ZnSnN2/GaN异质结的带阶具有方向依赖性；(4)研究了单原子层和双原子层ZnSnN2薄片的稳定性、结构和光电特征，PBE0杂化泛函计算表明单原子层和双原子层ZnSnN2薄片的带隙分别为2.39 eV和2.62 eV，均大于块体的带隙(1.79 eV)。我们的研究有助于深入理解基于Zn-IV-N2半导体的物质系统的性质，为其在光电子领域的应用奠定理论基础。