Electron affinity and band bending of single crystal diamond(111) surface

The electron affinity and band bending of a single crystal diamond (111) su rface have been investigated as a function of hydrogen coverage via work fu nction measurements, photoelectron yield spectroscopy, X-ray-excited photoe lectron spectroscopy (XPS), and low-energy electron diffraction (LEED). The hydrogen desorption and the 1 x 1-2 x 1 surface phase transition were achi eved by electron-beam irradiation at room temperature as well as annealing at high temperature. The electron affinity ranges from -1.27 eV for the ful ly hydrogen-covered 1 x 1 surface to 0.38 eV for the hydrogen-free 2 x 1 re constructed surface. Electron beam irradiation is demonstrated to be an eff ective method to induce hydrogen desorption and surface reconstruction. How ever, this irradiation process does not change the surface band bending on type IIb diamond, which is generally increased by annealing. It is conclude d that the electron-affinity change is caused by the C-II dipole layer, whe reas the band bending is not directly related to hydrogen coverage or recon struction but rather due to charged surface defects that are created simult aneously with the thermal treatment. (C) 1999 Elsevier Science S.A. All rig hts reserved.