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在激光分子束外延(LMBE)生长SrTiO3(STO)薄膜过程中,激光闪蒸出的Sr,Ti,O原子的微观反应过程及粒子形态是STO薄膜生长初期形成的关键.采用密度泛函理论中的广义梯度近似(DFT/GGA)方法,在PW91/DNP水平上研究了Sr,Ti,O原子在真空中的优先反应过程和形态,计算研究了SrO,TiO2和STO分子形成的反应机理,获得了相应的中间体和过渡态及反应活化能,并运用前线轨道理论分析了STO分子的形成机理.对比计算了STO分子可能的几何构型,得到了比较稳定的构型,其几何特征与STO单胞部分相似.计算研究表明,SrO,TiO2,STO分子是LMBE外延生长STO薄膜初期的主要粒子形态.
During the growth of SrTiO3 (STO) thin films by laser molecular beam epitaxy (LMBE), the microscopic reaction process and particle morphology of Sr, Ti and O atoms flashed by laser were the key to the formation of STO thin films. In the generalized gradient approximation (DFT / GGA) method, the preferential reaction process and morphology of Sr, Ti and O atoms in vacuum were studied at the PW91 / DNP level. The reaction mechanism of the formation of SrO, TiO2 and STO molecules was studied. The corresponding intermediates and transition states and the activation energies were also discussed and the formation mechanism of STO molecules was analyzed by using frontier orbital theory.The possible geometrical configurations of STO molecules were compared and the stable configuration was obtained.The geometric characteristics of STO molecules were compared with those of STO The results show that the SrO, TiO2 and STO molecules are the primary particle morphology of LMBE epitaxial growth STO thin films.