The Praperation Of Nb-doped TiO₂Ceramic Target And The Properties Investigation, Application Of The Deposited Films

TiO₂thin films were wildly used as the semiconductors and optical materials. In thispaper, the pure/2.5wt%Nb-doped TiO₂ceramics were prepared by Vacuum Sintering withthe temperature varied from1200℃to1400℃. The X ray diffractometer （XRD）,scanning electron microscope （SEM） and Four-point probe tester were applied to measurethe structural and electrical properties of the ceramics. The pure/Nb-doped TiO₂ceramicssintered at1200℃showed a typical rutile structure; as the temperature grew, the oxygenvacancies of the ceramics increased, which result in the appearance of thesub-stoichiometric titanium oxides at1350℃and1400℃for pure and Nb-doped TiO₂ceramices, respectively. Under the same sintering condition, the content of the rutile in theNb-doped TiO₂was higher than the TiO₂. As temperature rose from1200℃to1400℃,the roughness and the porosities declined with the growing of the surface particles of thepure/Nb-doped TiO₂ceramices. Four-point probe test analysis indicated that, when thetemperature was raised to1300℃, the resistivities of the pure/Nb-doped TiO₂ceramicswere decreased from1.9kΩ.cm and192Ω.cm to0.94Ω.cm and2.49×10^-3Ω.cm,respectively. Over1300℃, as the temperature grew, the resistivities of the pure/Nb-dopedTiO₂declined obviously. However, the Nb-doped TiO₂ceramic which was sintered at1300℃reached the conductivity requirement of the DC magnetron sputtering.Nb-doped TiO₂thin films were deposited on glass substrates by DCMS from theceramic sintered at1300℃. The surface morphology, structural and optical properties ofthe films deposited at different substrate temperature, DC power and Ar pressure wereinvestigatied by using XRD, SEM and optical transmission spectroscope. Until250℃, thecrystalinity of the Nb-doped TiO₂films were enhanced with the increase of substratetemperature; as the temperature varied from250℃to350℃, the transition of anataseâ†'rutile happened. The high DC power improved the crystalinity of the films; but, too higherpower also destroyed the formed films structure. With the Ar pressure rising to0.8Pa, thegrain sizes of the films were improved; over0.8Pa, the gain sizes decreased with the incease of pressure, oppositely. Optical properties analysis demonstrated that, thetransmittance of the anatase was obviously higher than that of the rutile; and the bettercrystallinity meant higher transmittance. The band gap was raised with the temperature upto250℃, and obtained the maximum3.78eV; when350℃, as the anatase transformed torutile, the band gap reduced to3.68eV. The increase of power raised the value of band gap.As the pressure grew, the band gap firstly declined, and got the minimum:3.69eV at0.3Pa; then, it increased step by step.The TFCalc designed Nb-doped TiO₂/SiO₂multilayer films were deposited by DCmagnetron sputtering, the structural and optical properties of the films were investigated.The results indicated: the properties of the deposited multilayer films are almost the sameas that of the ideal film; the regions with high reflection and the values of reflection werelittle smaller compared the ideal film; the high reflection region could beenlarged/norrowed by increasing/decreasing the sputtering time.