title: Giant alkali-metal-induced lattice relaxation as the driving force of the insulating phase of alkali-metal/Si(111):B.
abstract: Ab initio density-functional theory calculations, photoemission spectroscopy (PES), scanning tunneling microscopy, and spectroscopy (STM, STS) have been used to solve the 2sqrt[3]×2sqrt[3]R30 surface reconstruction observed previously by LEED on 0.5 ML K/Si:B. A large K-induced vertical lattice relaxation occurring only for 3/4 of Si adatoms is shown to quantitatively explain both the chemical shift of 1.14 eV and the ratio 1/3 measured on the two distinct B 1s core levels. A gap is observed between valence and conduction surface bands by ARPES and STS which is shown to have mainly a Si-B character. Finally, the calculated STM images agree with our experimental results. This work solves the controversy about the origin of the insulating ground state of alkali-metal/Si(111):B semiconducting interfaces which were believed previously to be related to many-body effects.
authors: Institut Jean Lamour UMR 7198, Nancy Université/CNRS, BP 70239 F-54506 Vandœuvre-lès-Nancy, France.
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authors: Chaput
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authors: Tournier-Colletta
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authors: Cardenas
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authors: Tejeda
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authors: Kierren
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authors: Malterre
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authors: Fagot-Revurat
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authors: Le Fèvre
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authors: Bertran
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authors: Taleb-Ibrahimi
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authors: Trabada
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authors: Ortega
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authors: Flores