FIZIKA A 8 (1999) 4 , 275-284

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PHOTON-STIMULATED DESORPTION OF HYDROGEN IONS FROM SEMICONDUCTOR SURFACES: EVIDENCE FOR DIRECT AND INDIRECT PROCESSES

M. PETRAVIÆa,A. HOFFMANb, G. COMTETc, L. HELLNERd and G. DUJARDINd

aDepartment of Electronic Materials Engineering, Research School of Physical Sciences and Engineering, The Australian National University, Canberra ACT 0200, Australia

bChemistry Department and The Solid State Institute, Technion, Haifa 32000, Israel

cLaboratoire pour l'Utilisation du Rayonnement Electromagnétique (LURE),
Bâtiment 209 D, Université de Paris-Sud, 91405 Orsay Cedex, France

dLaboratoire de Photophysique Moléculaire, CNRS, Bâtiment 213,
Université de Paris-Sud, 91405 Orsay Cedex, France

Dedicated to Professor Boran Leontiæ on the occasion of his 70th birthday

Received 22 November 1999; revised manuscript received 21 February 2000
Accepted 3 April 2000

Photon-stimulated desorption of positive hydrogen ions from hydrogenated diamond and GaAs surfaces have been studied for incident photon energies around core-level binding energies of substrate atoms. In the case of diamond surfaces, the comparison between the H+ yield and the near edge X-ray absorption fine structure (NEXAFS) for electrons of selected kinetic energies reveals two different processes leading to photodesorption: an indirect process involving secondary electrons from the bulk and a direct process involving core-level excitations of surface carbon atoms bonded to hydrogen. The comparison of H+ photodesorption and electron photoemission as the function of photon energy from polar and non-polar GaAs surfaces provides clear evidence for direct desorption processes initiated by ionisation of corresponding core levels of bonding atoms.

PACS numbers: 79.20.La, 79.70.+q
UDC 531.743.56

Keywords: desorption of positive hydrogen ions, photon-stimulated, hydrogenated diamond surface, GaAs surface, photon energies around core-level, direct and indirect processes
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