Electron spin resonance parameters of cation vacancies in tin dioxide doped with fluorine and hydrogen

Abstract

The spin Hamiltonian parameters of intrinsic defects in tin dioxide (SnO2) doped with fluorine or hydrogen are examined through the first-principles electronic structure calculations based on density functional theory (DFT). The electron paramagnetic resonance signals with g-tensor value in the range of 1.89–1.94 were found for tin vacancy (VSn) and its complex with oxygen vacancy (VSn-VO) associated with a donor like interstitial hydrogen or fluorine, substituting oxygen. The calculated parameters are consistent with experimental observations, which indicate that Sn vacancies may be present in SnO2 at essentially higher concentration than it is predicted by DFT based on the formation energies calculations. Within the second coordination shell of the tin vacancy, the VO may stabilize in the singly ionized charge state, which is otherwise considered to be unstable for isolated oxygen vacancy in the bulk of SnO2.

DFT calculations of tin dioxide crystals containing heavily-doped fluorine

“…This fact was not taken into account in Ref. 26 disallowing the direct comparison of results. DOS composition at the Fermi level is solely due to the Sn 5s AOs for the concentration interval between 1.56 mol.% and 12.50 mol.%.…”

“…Similar outcomes were obtained in another°uorine-doped SnO 2 computational study. 26 However, we are con¯dent that intra-atomic interaction for the strongly correlated Sn 4d-electrons by the UHF approximation (DFT þ U method) has to be considered in order to describe properly the tin dioxide crystal. This fact was not taken into account in Ref.…”

“…[22][23][24][25][26] These studies are rather important but do not reveal properties of the material at rather high impurity doping rates. Additionally, there exists some controversial experimental results suggesting that at rather high°uorine concentration n-type conductivity does not increase as it would be expected but tend to decrease.…”

Thermal desorption of molecular oxygen from SnO 2 (110) surface: Insights from first-principles calculations

“…In other words, even if O 2 molecule has already accepted one electron from the substrate, more charge is needed for quenching the magnetic interaction and further stabilization of the adsorbate. The obtained results can be rationalized assuming that adsorbed O 2 molecule breaks stoichiometry of the slab and can be considered in reality as a surface fractional cation vacancy, which according to our recent results [29] can induce magnetism in the nearest oxygen atoms. In principle, electronic charge acquired by the adsorbate may originate from donor type defects with variant donor levels in the band gap.…”

Impact of boron and indium doping on the structural, electronic and optical properties of SnO2

“…Apart from the experimental works, there are also many theoretical studies based on density functional theory (DFT) that examine the in uence of doping in SnO 2, mostly in substitutional positions [11][12][13][14][15][16][17] .…”