Effect of niobium doping on the structural, electrical and optical properties of epitaxial SnO2 films on MgF2 (110) substrates by MOCVD

Niobium (Nb)-doped SnO2 films were epitaxially grown on MgF2 (110) substrates by the metal organic chemical vapor deposition (MOCVD) technique. Structural, electrical and optical properties of the obtained films with different Nb-doping levels were investigated. The X-ray diffraction analysis revealed that the obtained films were rutile structure SnO2 grown along the (110) orientation. The epitaxial relationship between the Nb-doped SnO2 film and MgF2 substrate was clarified as SnO2 (110) || MgF2 (110) with SnO2 [001] || MgF2 [001] by the interface selected area electron diffraction measurement. A Hall mobility as high as 84 cm2 V−1 s−1 with the lowest resistivity of 2.9 × 10−3 Ω cm were obtained for the 4.3 at.% Nb-doped SnO2 film. The average optical transmittance in visible range of the 4.3 at.% Nb-doped SnO2 film exceeded 80% and the optical band gap was about 4.04 eV.