Inverse photoemission study of Be2C(100) and C60 on Be(0001) surfaces

• Main Authors: Hsin-Min Cheng, 鄭信民
• Other Authors: Ku-Ding Tsuei
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/34177205134373483437

碩士 === 國立清華大學 === 物理學系 === 88 === Abstract In the last few years, inverse photoemission spectroscopy (IPES) has rapidly emerged as an experimental technique capable of providing information about the unoccupied electronic band structure of solids. It can complement photoemission spectroscopy (PES), which provides information about the occupied electronic band. The insulating beryllium carbide (Be2C) thin films have been successfully prepared on a Be(0001) surface in our laboratory. We have carried out an extensive study on electronic state properties of Be2C(100) using IPES. From our experimental spectra, we observed step-like broad peaks due to umklapp process transition and no obvious dispersion relations. Therefore, we discussed these spectra by way of calculating one dimension (Γ-Ｘ ) density of state of Be2C(100). The conduction band minimum (CBM) of Be2C(100) was also determined to be 1.33eV above Femi level at point. We combined the CBM value with valence band maximum (VBM) (0.61eV below Femi level) from previous PES experiment, the indirect band gap of Be2C(100) was determined to be 1.94eV. Furthermore, we also observed that the C60 monolayer is metallic on Be(0001) surface, and minimal charge transfer from beryllium substrate to C60. Some photographs of low energy electron diffraction (LEED) patterns will help us to understand the constructions of C60 adsorbate and beryllium carbide.