掺杂与应力对ZrO2薄膜电子结构和光学性质的影响

利用基于密度泛函理论的第一性原理平面波超软赝势方法系统地研究了掺杂和应力对ZrO_2薄膜的电子结构与光学性质的影响.本文首先研究了Hf原子替代掺杂对ZrO_2薄膜物性的影响,研究结果表明,Hf原子掺杂减小了ZrO_2薄膜的带隙和态密度大小,可在一定程度上降低其表面缺陷电荷和漏电流.掺杂Hf原子后介电峰和吸收峰的值明显下降,同时介电峰和吸收峰的波形均出现了窄化现象,半高宽显著减小.本文也着重研究了不同应力下四方晶相ZrO_2薄膜物理性质变化及规律.研究发现压应力显著调控了ZrO_2薄膜的带隙以及价带顶和导带底附近的能带结构.施加应力后吸收峰的吸收范围和强度均显著增大,峰值对应的光子能量蓝移则表明对紫外光的吸收随着应力的增加有所增强.在低能量红外和可见光区域,施加压应力后ZrO_2薄膜的折射率变大,但在紫外线区域,压应力使ZrO_2薄膜的折射率呈现出先增大后减小的波动特性.上述研究结果为ZrO_2薄膜材料的设计与应用提供了理论依据.

Effects of doping and stress on electronic structure and optical properties of ZrO2 thin films

The influences of doping and stress on the electronic structure and optical properties of ZrO2 thin films were systematically studied by using the first-principles plane-wave ultra-soft pseudopotential method based on density functional theory. In this paper, the effect of Hf atom substitution doping on the physical properties of ZrO2 films is studied. The results show that Hf atom doping can reduce the band gap and density of states of ZrO2 films, which can reduce the surface defect charge and leakage current to some extent. The values of dielectric peak and absorption peak are significantly decreased after doping Hf atoms, and the waveforms of dielectric peak and absorption peak are narrowed, and the full wave at half maximum (FWHM) is significantly reduced. This paper also focuses on the physical properties and regularity of tetragonal ZrO2 films under different stresses. It is found that the compressive stress significantly regulates the band gap of the ZrO2 film and the band structures near the top of valence band and the bottom of the conduction band. After the stress is applied, the absorption range and absorption intensity of the absorption peak are significantly increased. The blue shift of the photon energy corresponding to the peak indicates that the absorption of ultraviolet light is enhanced with the increase of stress. In the low-energy infrared and visible light regions, the refractive index of ZrO2 film becomes larger after applying compressive stress, but in the ultraviolet region, the compressive stress causes the refractive index of ZrO2 film to increase first and then decrease. The above research results provide a theoretical basis for the design and application of ZrO2 thin film materials.