CAJ | 학술논문

采用基于密度泛函理论的第一性原理方法，在局域密度近似（LDA ）下研究了厚度为0.626～2.711nm （100）面BaHfO3薄膜的电子结构、光学和弹性性质．电子结构和光学性质计算结果表明：以BaO为表面层原子的BaHfO3纳米薄膜均为直接带隙半导体材料，带隙随薄膜厚度减小而逐渐减小，表现出明显的量子尺寸效应，此时薄膜的光学吸收边发生红移，吸收带出现窄化现象．以 HfO2作为表面层原子的BaHfO3薄膜则属于间接带隙半导体材料，且带隙随薄膜厚度减小而微弱增加．弹性性质计算结果表明：体弹模量、剪切模量和杨氏模量等表征材料硬度的力学参数均随BaHfO3纳米薄膜厚度减小而显著减小，呈现尺寸效应．电荷密度分布分析揭示了薄膜厚度改变了BaHfO3纳米薄膜的价键特性，这是材料硬度改变的内在原因．该研究结果为BaHfO3纳米薄膜材料的设计与应用提供了理论依据．
채용기우밀도범함이론적제일성원리방법，재국역밀도근사（LDA ）하연구료후도위0.626～2.711nm （100）면BaHfO3박막적전자결구、광학화탄성성질．전자결구화광학성질계산결과표명：이BaO위표면층원자적BaHfO3납미박막균위직접대극반도체재료，대극수박막후도감소이축점감소，표현출명현적양자척촌효응，차시박막적광학흡수변발생홍이，흡수대출현착화현상．이 HfO2작위표면층원자적BaHfO3박막칙속우간접대극반도체재료，차대극수박막후도감소이미약증가．탄성성질계산결과표명：체탄모량、전절모량화양씨모량등표정재료경도적역학삼수균수BaHfO3납미박막후도감소이현저감소，정현척촌효응．전하밀도분포분석게시료박막후도개변료BaHfO3납미박막적개건특성，저시재료경도개변적내재원인．해연구결과위BaHfO3납미박막재료적설계여응용제공료이론의거．
The electronic structure ,optical and elastic properties of the (100) surface of BaHfO3 nano-films in large thickness range of 0.626~2.711nm were investigated by first-principles calculations based on density functional theory with the localized density approximation (LDA ) .The calculated results of the electronic structure and optical properties indicate that BaHfO3 nanofilms with BaO termination are direct-band-gap semiconductors , and as the film thickness decreases , the band gap decreases , w hich show nanofilms have obvious quantum size effect ,and then red shift of the optical absorption edge is ob-served in the absorption spectra of BaHfO3 nanofilms ,accompanying with the narrowing of the absorp-tion band .However ,BaHfO3 nanofilms with HfO2 termination are indirect-band-gap semiconductors , and the band gap slightly increases with the film thickness decreases .The calculated results of the elas-tic properties show that bulk modulus ,shear modulus and Young's modulus ,w hich characterize the ma-terial hardness ,are highly size dependent ,and are significantly reduced with decreasing the thickness . Electron density distribution analysis reveals that the thickness of BaHfO 3 nanofilms changes the valence electron concentration distribution of the system ,and this is the underlying reason for the change of hardness of the materials .Thus ,changing the thickness of the film can effectively control the energy gap and hardness of the system .The results of the study provide a theoretical basis for design and appli-cation of BaHfO3 nanomaterials .