Electrical and optical properties of N-doped SnO2 thin films prepared by magnetron sputtering

Tin oxide (SnO2) and nitrogen-doped tin oxide (N:SnO2) films were deposited using RF-magnetron sputtering. By adjusting the oxygen partial pressure from 0% to 3%, a series of samples were prepared. With the help of SEM, XRD, four-point probes and spectrophotometer, microstructure, electrical and optical properties were investigated. XRD patterns indicated that both SnO2 and N:SnO2 films were mainly rutile structure. The orientation of SnO2 films was transformed from the (101) under low oxygen pressure to the (110) under higher pressure. However, only (101) peak was observed in N:SnO2 films. The transmittance of the films was about 80% in the visible region. The optical band gap of SnO2 films increased from 4.02 eV to 4.08 eV as the oxygen partial pressure decreased from 3% to 0%. While for the N:SnO2 films, the optical band gap values increased from 3.60 eV to 3.95 eV. The electrical resistivity reached minimum values of 3.1 × 10− 2 Ω·cm and 5.9 × 10− 3 Ω·cm respectively for SnO2 and N:SnO2 films.

► N-doped SnO2 films had deposited under oxygen partial pressure from 0% to 3%.
► N-doping would change the growth orientation of films from (110) to (101).
► The resistivity decreased to the lowest value of 5.86 × 10− 3 Ω·cm after N-doping.
► The optical band gap decreased to the lowest value of 3.6 eV after N-doping.