Structural,photoelectrical and photoluminescence properties of Ta-doped SnO2 monocrystal films grown on MgF2 (110) substrates

Epitaxial Ta-doped SnO₂ films with Ta concentrations from 0 to 8?at.% have been deposited on MgF₂ (110) substrates by the metal-organic chemical vapor deposition (MOCVD) method. The effects of Ta doping on the structural, photoelectrical and photoluminescence (PL) properties of the obtained films were studied in detail. The results showed that the single crystal rutile SnO₂ films were obtained and the heteroepitaxial relationship was SnO₂ (110) || MgF₂ (110) with SnO₂ 001] || MgF₂ 001]. The highest Hall mobility of 74.2?cm²?V^?1?s^?1 was achieved for the 5?at.% Ta-doped SnO₂ film and the minimum resistivity as low as 2.5?×?10^?4?Ω?cm was obtained at 6?at.% of Ta-doping. In the visible region, all the obtained films had average transmittances exceeding 87%. As the Ta concentration increased from 0 to 8?at.%, the optical band gap of the films rose from 3.89 to 4.32?eV. The room temperature PL spectra of Ta-doped SnO₂ films showed intense green emission, weak violet and yellow emissions. The corresponding PL mechanisms were discussed.