In2O3晶体电子结构和光吸收机理研究

为了得到准确的In₂O₃晶体电子结构, 本文分别采用GGA, GGA+U, HSE06的方法计算了电子结构, 并进行了G₀W₀修正, 通过比较计算结果, 得到HSE06+G₀W₀方法计算得到的禁带宽带最接近实验结果. 在此基础上使用Hedin的G₀W₀近似方法和Bethe-Salpeter方程计算得到了In₂O₃晶体的光学性质, 计算结果与实验结果吻合很好, 在此基础上通过对准粒子能带结构、光学跃迁矩阵和光学吸收谱的分析, 给出了In₂O₃晶体的光学跃迁机理.

Study on the electronic structures and the optical absorption mechanism of In2O3 crystals

Indium oxide with its wide gap is a multifunctional semiconductor material, which has gained application in many areas. Indium oxide films show high electrical property and high transparency, which have been applied in OLED display, flat-panel display, thin film solar cells, etc. However, the mechanisms of both high electrical and high transparent properties are still not clear up to now. So in this paper, the electronic structures of the In₂O₃ crystals are studied by GGA, GGA+U, HSE06 and G₀W₀ corrections. The mechanisms of optical transition and formation of transparent electrode in In₂O₃ crystals are studied using Hedin's G₀W₀ approximation and the Bethe-Salpeter equation. The complex refractive index, complex dielectric function and optical absorption spectrum of the In₂O₃ crystal have been obtained, which are in good agreement with experimental results. By analyzing the quasi-particle band structures, optical transition matrix and optical absorption spectrum, the mechanisms of optical transition and formation of transparent electrode in In₂O₃ can be interpreted. BSE (Bethe-Salpeter equation) calculation results show that the transition from Γ₈ to Γ₁ is permitted, however, the transition probability is far less than that from Γ₁₀ to Γ₁. This is because, for Γ₈ to Γ₁ transition, there are three even symmetry bands and two odd symmetry bands, in which only the transition from two odd symmetry bands to the conduction band is permitted. Other causes for this phenomenon are that in the In₂O₃ primitive cell there exist some overlapping bands, which result in the false transition. Therefore, this work argues that in the In₂O₃ crystals optical band gap is 4.167 eV, which corresponds to the direct transition from Γ₁₀ to Γ₁. This result will help understand the mechanisms of optical transition and the transparent electrode in In₂O₃.