Structure, properties, and dynamics of oxygen vacancies in amorphous SiO2.
Oxygen vacancies in SiO2 have long been regarded as bistable, forming a Si-Si dimer when neutral and a puckered configuration when positively charged. We report first-principles calculations of O vacancies in amorphous SiO2 supercells that unveil significantly more complex behavior. We find that the vast majority of O vacancies do not pucker after capture of a hole, but are shallow traps. The remaining vacancies exhibit two distinct types of puckering. Upon capturing an electron, one type forms a metastable dipole, while the other collapses to a dimer. A statistical distribution of O vacancies is obtained, and the implications for charge transport and trapping in SiO2 are discussed.
Lu
Zhong-Yi
ZY
Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
Nicklaw
C J
CJ
Fleetwood
D M
DM
Schrimpf
R D
RD
Pantelides
S T
ST