6H-SiC(0001)-63^(1/3)×63^(1/3)R30°重构表面的同步辐射角分辨光电子能谱研究

Synchrotron radiation angle-resolved photoelectron spectroscopy studies of 6H-SiC(0001)-63^(1/3)×63^(1/3)R30° surface

利用同步辐射角分辨光电子能谱(SRARPES)对6H-SiC(0001)-63^(1/3)×63^(1/3)R30°重构表面的电子结构和表面态进行了研究.通过鉴别价带谱中来自于体态的信息,可以推断出重构表面的费米能级位于体态价带顶之上(2.1±0.1)eV处.实验测出的体能带结构与理论计算的结果较为符合.在重构表面上发现三个表面态,分别位于结合能-0.48eV(S0),-1.62eV(S1)和-4.93eV(S2)处.沿着表面布里渊区的高对称线ΓKM方向,测量了相关表面态的能带色散,只有表面态S0(-0.48eV)表现出了所希望的63×63R30°重构周期性.根据实验现象,可以认为,表面态S0应归结于重构表面的C—C悬键,而表面态S1则由重构表面未钝化的C悬键所导致.

The electronic structure including some surface states of the 6√3×6√3R30° reconstructed 6H-SiC（0001 ） surface have been investigated by synchrotron radiation angle-resolved photoelectron spectroscopy （ SRARPES）. The energy position of the bulk valence band maximum （VBM） is determined to be at （ - 2.1 ± 0.1 ） eV related to the Fermi level by identifying bulk states from valence band spectra. The experimentally measured bulk energy band structure agrees well with the theoretical calculation result. Three surface states are clearly identified at the binding energies of -0.48 eV （So）, - 1.62 eV （$1） and - 4.93 eV （ S2 ） referred to the Fermi level. The surface state dispersion is measured along Г K M, the high symmetry lines of the surface Brillouin zone. Only surface state So（ -0.48 eV） shows expected 6√3×6√3R30° periodicity in all probed SBZ. Surface state So should be attributed to the C--C dangling bonds of the surface reconstruction. Surface states St should be attributed to the unsaturated C dangling bonds.