Oxygen vacancy defects in tantalum pentoxide: a density functional study
R. Ramprasad
, 
, a, Michael Saddb, Doug Robertsb, Tom Remmela, Mark Raymondb, Eric Luckowskib, Sriram Kalpatb, Carole Barronb and Mel Millera
a Motorola Semiconductor Products Sector, 2100 E. Elliot Road, Tempe, AZ 85284, USA
b Motorola Semiconductor Products Sector, 3501 Ed Bluestein Blvd, Austin, TX 78721, USA
Available online 14 June 2003.
First principles total energy calculations were performed in order to characterize O vacancy defects in Ta2O5. A simplified version of the crystalline orthorhombic phase of Ta2O5 was used in this study. Results indicate that O vacancies in Ta2O5 can be broadly classified based on their location in the lattice. One type of vacancy (occupying the `in-plane' sites) displays deep or mid gap occupied states, and shallow unoccupied states, while a second type (occupying `cap' sites) results in shallow occupied states. For a wide range of local Fermi level or chemical potential, the neutral and +2 charged states of the in-plane type vacancy and the +2 charge state of the cap type vacancy are found to be most stable.
Author Keywords: Defect states; Trap states; Tantalum pentoxide; Oxygen vacancy; Density functional theory
