Study on the preparation and properties of antireflective ITO thin films by magnetron sputtering
LI Shi-tao,QIAO Xue-liang,CHEN Jian-guo,WANG Hong-shui,JIA Fang (State Key Lab of Die & Mould Technology,Huazhong University of Science and Technology,Wuhan 430074,China)
Highly transparent and conductive ITO (indium-tin oxide) films were deposited on glass substrate at room temperature (R.T.) by magnetron sputtering, and the target was indium-tin oxide (In2O3: SnO2=1:1) made by sintered. The Ar gas pressure (PAr) varies from 0.2~3.0Pa and the oxygen flux (fO2) varies in range of 0~10sccm controlled by gas mass flowmeter. Furthermore the detailed investigation was carried out for the effects of PAr and fO2 on ITO films. It is concluded that fO2 value not only affects refractive index (n) due to carrier concentration variation in ITO films but also affects the deposition rate because of sputtering threshold and free length Ar+. Substrate surface roughness has an important influence on the refractive index, the minimum refractive index is 1.97 which approaches the optical matching when PAr=0.8Pa and fO2=2.4sccm. The maximal transmittance of ITO film is 89.4% in visible light spectrum, the square resistance Rs=75.9?/□, resistivity ρ =8.8×10-4?·cm when the thickness of ITO film is 241.5nm. AFM analysis show that the spikes and needles on thin film are few and ITO film surface is smooth.