Microstructure and properties of indium tin oxide thin films deposited by RF-magnetron sputtering

摘要

Tin-doped indium oxide (ITO) thin films were prepared using conventional radio frequency (RF) planar magnetron sputtering equipped with IR irradiation using a ceramic target of In_2O_3 SnO_2 with a mass ratio of 1:1 at various IR irradiation temperatures T_I (from room temperature to 400 deg C). The refractive index, deposited ratio, and resistivity are functions of the sputtering Ar gas pressure. The microstructure of ITO thin films is related to IR T_I, the crystalline seeds appear at T_I = 300 deg C, and the films are amorphous at the temperature ranging from 27 deg C to 400 deg C. AFM investigation shows that the roughness value of peak-valley of ITO thin film {R_(p-v)) and the surface microstructure of ITO thin films have a close relation with T_I. The IR irradiation results in a widening value of band-gap energy due to Burstein-Moss effect and the maximum visible transmittance shifts toward a shorter wavelength along with a decrease in the film's refractive index. The plasma wavelength and the refractive index of ITO thin films are relative to the T_I. XPS investigation shows that the photoelectro-lytic properties can be deteriorated by the sub-oxides. The deterioration can be decreased by increasing the oxygen flow rate (fo_2), and the mole ratio of Sn In in the samples reduces with an increase in fo_2.