Synthesis of disilicide single crystal thin films with a new silicon network and study on its electronic structure

碱土金属和稀土金属Ca、Sr、La在Si衬底上蒸发形成具有不同于金刚石型网络的新型多种Si网络的MSi_2 （M = Ca, Sr, La）外延膜。虽然在元素周期表中位于Si之上的碳可以形成各种各样的网络，如石墨、C_<60>和碳纳米管，但已知的只有Si的金刚石型网络。本研究的目的是生长MSi_2 （M = Ca, Sr, La）外延薄膜，并研究其随Si网络和位于Si网络之间的M离子的电子能带结构。首先，我们尝试通过将Ca蒸发到Si（111）衬底上来生长CaSi_2/Si（111）外延薄膜。利用反射高能量电子衍射（RHEED）和埃歇电子能谱（AES）找到了生长条件，在衬底温度为600℃、蒸发速率为0.06 ~ 0.08 Å/s的条件下成功地生长出了CaSi_2/Si（111）外延薄膜。本文在广岛大学广岛同步辐射中心历史系对生长在BL7和BL9光束线上的外延薄膜进行了角分辨光发射光谱（ARPES）研究。随着蒸发Ca离子厚度的增加，θ可以观察到Ca 3d态和Si 3p态之间的杂化带穿过费米能级（E_F）。实验结果与基于LPAW[1]的带结构计算得到的带色散大致对应。我们发现，随着0的增加，费米波数增加。此外，我们还成功地观测到六重对称的费米表面，反射CaSi_2/Si的表面（111）。在CaSi_2/Si（111）的实验之后，我们开始了SrSi_2/Si（111）的实验。在700℃的衬底温度下，我们检测了SrSi_2/Si（111）薄膜的能带色散。接下来，我们计划通过改变衬底Si.[1]的M和取向来系统地研究MSi_2/Si的电子结构S. Fahy和D. R. Hamann，物理学家。Rev. B 41,7587（1990）。少

Evaporation of alkali earth metals and rare earth metals such as Ca, Sr and La on Si substrates forms MSi_2 (M = Ca, Sr, La) epitaxial film with a new various Si network, different from the diamond-type network. Although, carbon, which locates just above Si in the periodic table, forms a various network such as graphite, C_<60> and carbon nanotube, only diamond-type network has been known for Si. The purpose of the present study is to grow MSi_2 (M = Ca, Sr, La) epitaxial films and to study its electronic band structure depending on the Si network and the M ion located between the Si networks.First, we have attempted to grow CaSi_2/Si(111) epitaxial films by evaporating Ca onto the Si(111) substrates. We have found the growth condition by using RHEED (Reflection High Energy Electron Diffraction) and AES (Auger Electron Spectroscopy) and succeeded in the growth of CaSi_2/Si(111) epitaxial films with a substrate temperature of 600 ℃ and the evaporation rate of 0.06-0.08 Å/s. We have carr … More ied out on angle-resolved photoemission spectroscopy (ARPES) for the grown epitaxial films on beamlines BL7 and BL9 at HiSOR of Hiroshima Synchrotron Radiation Center, Hiroshima University. With increasing the thickness of the evaporated Ca ion, θ, the hybridization band between the Ca 3d and Si 3p states, crossing the Fermi level (E_F), is observed. The experimental results roughly correspond to the band dispersion derived from the band-structure calculation based on LPAW [1]. We have found that with increasing 0, the Fermi wave number increases. In addition, we have succeeded in the observation of the Fermi surface with a six-fold symmetry, reflecting the surface of CaSi_2/Si(111).After the experiments for CaSi_2/Si(111), we moved to study for SrSi_2/Si(111). Now, we have detected the band dispersion of SrSi_2/Si(111) films grown at the substrate temperature of 700 ℃. Continuously, we plan to investigate systematically the electronic structure of MSi_2/Si by changing M and orientations of the substrate Si.[1] S. Fahy and D. R. Hamann, Phys. Rev. B 41, 7587 (1990). Less