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如Ca、Sr、La等在Si衬底上蒸发形成具有不同于金刚石型网络的新型Si网络的MSi_2（M = Ca、Sr、La）外延膜。尽管在元素周期表中位于Si上方的碳形成了各种网络，如石墨、C_2<60>和碳纳米管，但对于Si而言，仅已知金刚石型网络。本研究的目的是生长MSi_2（M = Ca，Sr，La）外延薄膜，并研究其电子能带结构对Si网络和位于Si网络之间的M离子的依赖性。利用反射高能电子衍射（RHEED）和俄歇电子能谱（AES）确定了生长条件，在衬底温度为600 ℃，蒸发速率为0.06-0.08 μ m/s的条件下成功地生长了CaSi_2/Si（111）外延膜。我们有卡尔 ...更多信息 利用角分辨光电子能谱（ARPES）对广岛大学广岛同步辐射中心的希索实验室在BL 7和BL 9光束线上生长的外延薄膜进行了研究。随着蒸发Ca离子厚度θ的增加，观察到Ca 3d态和Si 3 p态之间的杂化带，该杂化带穿过费米能级（E_F）。实验结果大致对应于基于LPAW的能带结构计算得到的能带色散[1]。我们发现，随着0的增加，费米波数增加。此外，我们还成功地观察到了CaSi_2/Si（111）表面的六重对称费米面，在CaSi_2/Si（111）的实验之后，我们又对SrSi_2/Si（111）进行了研究。在700 ℃衬底温度下生长的SrSi_2/Si（111）薄膜中，我们检测到了能带色散。接下来，我们计划通过改变衬底Si的M和取向来系统地研究MSi_2/Si的电子结构。[1]S. Fahy和D. R. Hamann，Phys. 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