TY - JOUR

T1 - Role of boron and (√3×√3)-B surface defects on the growth mode of Si on Si(111)

T2 - A photoemission and electron diffraction study

AU - Fissel, Andreas

AU - Krügener, Jan

AU - Schwendt, Dominik

AU - Osten, H. Jörg

PY - 2010/2

Y1 - 2010/2

N2 - The influence of boron on Si molecular beam epitaxy was investigated as function of coverage and temperature by reflection high-energy electron diffraction (RHEED). The development of the boron-covered Si surface was studied additionally by ultraviolet photo electron spectroscopy (UPS) as function of boron coverage (c B) and annealing condition. We found a direct correlation between the appearance of surface states in UPS and the transient growth behaviour observed in RHEED. For c B > 0.4 monolayer (ML) regular RHEED oscillations occur with a period typically for two bilayers (BLs), whereas for lower c B a transient behaviour with irregular intensity oscillations was observed in the initial growth stages. The appearance of this transient behaviour is discussed in terms of an initial surface defect-induced nucleation of BL-high Si islands and the formation of two BLs-high Si islands on top of the van der Waals-like perfect boron-covered surface, respectively. The occurrence of surface defects for c B < 0.6 ML is clearly established in UPS measurements, where an intensity peak slightly below the Fermi level (-0.4 eV) was visible. We suggest that this surface defect level is related to Si adatom dangling bonds acting also as preferential nucleation centres in epitaxy. Furthermore, surface defects results in a significant Fermi level pinning.

AB - The influence of boron on Si molecular beam epitaxy was investigated as function of coverage and temperature by reflection high-energy electron diffraction (RHEED). The development of the boron-covered Si surface was studied additionally by ultraviolet photo electron spectroscopy (UPS) as function of boron coverage (c B) and annealing condition. We found a direct correlation between the appearance of surface states in UPS and the transient growth behaviour observed in RHEED. For c B > 0.4 monolayer (ML) regular RHEED oscillations occur with a period typically for two bilayers (BLs), whereas for lower c B a transient behaviour with irregular intensity oscillations was observed in the initial growth stages. The appearance of this transient behaviour is discussed in terms of an initial surface defect-induced nucleation of BL-high Si islands and the formation of two BLs-high Si islands on top of the van der Waals-like perfect boron-covered surface, respectively. The occurrence of surface defects for c B < 0.6 ML is clearly established in UPS measurements, where an intensity peak slightly below the Fermi level (-0.4 eV) was visible. We suggest that this surface defect level is related to Si adatom dangling bonds acting also as preferential nucleation centres in epitaxy. Furthermore, surface defects results in a significant Fermi level pinning.

UR - http://www.scopus.com/inward/record.url?scp=76949106429&partnerID=8YFLogxK

U2 - 10.1002/pssa.200982433

DO - 10.1002/pssa.200982433

M3 - Article

AN - SCOPUS:76949106429

VL - 207

SP - 245

EP - 253

JO - Physica Status Solidi (A) Applications and Materials Science

JF - Physica Status Solidi (A) Applications and Materials Science

SN - 1862-6300

IS - 2

ER -