Electron-stimulated desorption from an unexpected source: Internal hot electrons for Br-Si(1 0 0)-(2 × 1) |
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Authors: | BR Trenhaile |
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Institution: | Department of Physics, Department of Materials Science and Engineering, and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States |
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Abstract: | The desorption of Br adatoms from Br-saturated Si(1 0 0)-(2 × 1) was studied with scanning tunneling microscopy as a function of dopant type, dopant concentration, and temperature for 620-775 K. Analysis yields the activation energies and prefactors for desorption, and the former correspond to the energy separation between the Fermi level and Si-Br antibonding states. Thus, electron capture in long-lived states results in Br expulsion via a Franck-Condon transition. Analysis of the prefactors reveals that optical phonons provide the energy needed for the electronic excitation. These results show that desorption induced by an electronic transition can occur in closed system without external stimulus, and they indicate that thermally-excited charge carriers may play a general role in surface reactions. |
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Keywords: | Scanning tunneling microscopy Desorption induced by electronic transitions Thermal desorption Br-Si(1 0 0)-(2 × 1) |
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