ANGLE-RESOLVED PHOTOEMISSION OF DIAMOND (111) AND (100) SURFACES - NEGATIVE ELECTRON-AFFINITY AND BAND-STRUCTURE MEASUREMENTS

Angle-resolved photoemission from both (100) and (111) oriented, natural type IIb diamond was used to study the electronic structure of diamond. A negative electron affinity (NEA) was found on the 2X1 reconstructed diamond (100) surface. Photoemission spectra of NEA surfaces exhibit a distinctive peak due to emission from the conduction band edge. This peak was used as a reference point to correlate spectra of (100) and (111) surfaces with a NEA. A feature at approximately 7.5 eV above the conduction band edge appears in the spectra of both the (111) and (100) surfaces. Angle-resolved photoemission measurements were used to determine the energy dispersion of this feature for various off-normal angles. The results for the surfaces were correlated, and compared to a calculated band structure. Based on this comparison we attribute this feature to emission from secondary electrons which are collected in a conduction band level at approximately 7.5 eV above the conduction band edge.