Studies on Carrier Trap Levels at Ultrathin SiO_2/Si Interface and Its Relation with Microscopic Structures

(1)在900℃以下，氧化应力导致表面粗糙度增加。此外，根据界面结构的周期性变化，在Si（100）上形成的氧化物的表面粗糙度以0.19nm的厚度周期振荡。(2)SiO_2/Si（100）界面处的界面粗糙度产生了界面态。此外，还探测到了与SiO_2/Si（111）界面结构相关的界面态。(3)价带与O2 s芯能级之间的能量差比体相SiO_2的相应能量差大0.2eV。根据第一性原理分子轨道计算，这种差异可归因于SiO_2/Si界面附近约135度的窄四面体间键角。此外，在由处于中间氧化态的Si原子限定的界面处的两种类型的原子结构之间的价带偏移相差约0.17 eV。手风琴 关于我们 根据第一原理分子轨道计算，这种差异可以归因于通过去极化效应，在特征为包含最大量的处于3+氧化态（Si^<3+>）的Si原子的界面处的界面偶极子比在特征为包含最大量的处于1+氧化态（Si^<1+>）的Si原子的界面处的界面偶极子小。(4)通过对Si 2 p光电子在氧化硅中的弹性散射和非弹性散射路径的Monte Carlo计算，模拟了氧化引起的光电子衍射花样的变化，发现总的弹性散射截面和非弹性散射截面分别为1.54×10^m ^2<-20>和1.26×10^<-20>m ^2。(5)在相同的氧化条件下，氧化速率随氧化进程呈周期性变化，在特定的界面结构处显著降低。氧化速率受SiO_2/Si界面结构的影响。少

(1) Below 900℃ the oxidation-induced-stress causes the increase in surface roughness. Furthermore, the surface roughness of oxide formed on Si (100) oscillates with period in thickness of 0.19 nm in accordance with periodic changes in the interface structures. (2) The interface roughness at SiO_2/Si (100) interface produces the interface states. In addition, the interface states correlated with SiO_2/Si (111) interface structures were detected. (3) The energy difference between the bonding states in the valence-band and the O 2s core-level is larger than the corresponding difference for the bulk SiO_2 by about 0.2 eV.According to a first-principle molecular orbital calculations this difference can be attributed to a narrow intertetrahedral bond angle of about 135 degrees near the SiO_2/Si interfaces. Furthermore, the valence-band offset differs by about 0.17 eV between the two types of atomic structures at the interface defined by the Si atoms in intermediate-oxidation states. Accordin … More g to a first-principle molecular orbital calculations this difference can be attributed to smaller interface dipole at the interface which is characterized as containing a maximum amount of Si atoms in 3+ oxidation states (Si^<3+>) than that at the interface which is characterized as containing a maximum amount of Si atoms in 1+ oxidation states (Si^<1+>) through the depolarization effect. (4) It was found from the Monte Carlo calculation of path of elastically and inelastically scattered Si 2p photoelectrons in silicon oxide for the simulation of oxidation-induced changes in photoelectron diffraction patterns that the total elastic scattering cross-section and the inelastic scattering cross-section are 1.54×10^<-20> and 1.26×10^<-20> m^2, respectively. (5) At the same oxidation condition the oxidation rate changes periodically with the progress of oxidation and decreases significantly at specific interface structures. In other words, the oxidation rate is influenced by the SiO_2/Si interface structures. Less