Regensburg 1998 – scientific programme

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HL: Halbleiterphysik

HL 32: Diamant

HL 32.8: Talk

Thursday, March 26, 1998, 18:15–18:30, H14

Dehydrogenation, Reconstruction and Electron Affinity of Diamond (100) and (111) Surfaces — •J.B. Cui, K. Amtmann, J. Kinsky, J. Ristein, and L. Ley — Institut f"ur Technische Physik, Universit"at Erlangen-N"urnberg, Erwin-Rommel-Str. 1, D-91058 Erlangen

It is meanwhile accepted that the hydrogen passivation of diamond is the key parameter for the structural and electronic properties of the (100) and (111) surface of the material. The presence of hydrogen has influence on the reconstruction of the surfaces and leads under certain conditions to a negative electron affinity (NEA) as witnessed qualitatively in many experiments. In the present work we have determined the electron affinity of diamond (100) and (111) surfaces quantitatively by combining photoemission and work function measurements on type II b single crystals after plasma hydrogenation and various subsequent annealing steps. Concomitantly, the thermally induced structural transition of the surfaces was investigated by LEED and the relative intensity of that core level component which is characteristic for the clean surface. Since all these experiments require ultrahigh vacuum conditions accurate temperature determination of the diamond surface is a non trivial task which was approached by in situ Raman measurement of the Stokes shift. The results exhibit a complicated temperature dependence of the electron affinity, the LEED pattern and the surface core level intensity.