Optimisation of surface treatments of TiO₂:Nb transparent conductive coatings by a post-hot-wire annealing in a reducing H₂ atmosphere

详细信息    查看全文

• 作者：M.V. Castro ; L. Rebouta ; P. Alpuim ; M.F. Cerqueira ; M. Benelmekki ; C.B. Garcia ; E. Alves ; N.P. Barradas ; E. Xuriguera ; C.J. Tavares
• 关键词：Niobium ; Titanium dioxide ; Hot-wire ; Transparent conducting oxide ; Electrical properties ; Reactive sputtering ; Hydrogen ; Annealing
• 刊名：Thin Solid Films
• 出版年：1 January, 2014
• 年：2014
• 卷：550
• 期：Complete
• 页码：404-412
• 全文大小：1137 K

文摘

Transparent and electrically conductive niobium-doped TiO₂ thin films have been deposited on glass surfaces by d.c.-pulsed reactive magnetron sputtering from a composite Ti:Nb target, using oxygen as reactive gas. A rapid 1 min annealing at 500 掳C in an atomic hydrogen rich atmosphere, obtained by flowing H₂ on a Ta filament resistively heated to 1750 掳C in vacuum (hot-wire), proved to be very efficient in enhancing the electrical properties of these ~ 100 nm thick TiO₂:Nb thin films. Dark conductivity (蟽_d) and its activation energy were measured as a function of (inverse) temperature and the value of 蟽_d at room temperature was used to assess the effect of the H₂ annealing on the transport properties. A 5-order of magnitude increase in electrical conductivity was observed for optimised treatment conditions at a hydrogen pressure of 10 Pa. A maximum value of 蟽_d in the range of ~ 1.4 脳 10p>3p> S/cm was attained for optimised conditions, where a level of ~ 6 at.% of H doping was measured close to the film surface. X-ray photoelectron spectroscopy, elastic recoil detection analysis, Rutherford backscattering and Raman spectroscopies were used to access information of composition and film structure for the explanation of the strong enhancement of the film's electrical conductivity and band-gap widening to 3.45 eV following hot-wire treatments. These thin films can be used as transparent conductive oxide contact layers for photovoltaic applications.