Effect of Sb doping on structural, electrical and optical properties of epitaxial SnO_2 films grown on r-cut sapphire

摘要

Antimony-doped tin oxide (SnO_2:Sb) films have been epitaxially grown on r-cut sapphire substrates by metalorganic chemical vapor deposition (MOCVD). Although the films were all (101) oriented with rutile structure, they showed different microstructure, electrical and optical properties as Sb doping varied from 0% to 7%. The doping of Sb could reduce the formation of (101) twins in SnO_2 films. The SnO_2:Sb film with the lowest resistivity of 1.3 × 10~(-3) Ω cm and the highest carrier concentration of 2.5 × 10~(20) cm~(-3) was obtained at 5% Sb-doping. The undoped and Sb-doped SnO_2 films exhibited different electrical transport mechanism. The samples showed high transparency of ~80% in the visible range. As Sb concentration increased, the absorption edge of the films shifted to shorter wavelength and the calculated optical band gaps were about 3.77-4.11 eV.