钽掺杂二氧化钛薄膜的光电性能研究

Optoelectrical properties of tantalum-doped TiO_2 thin films

采用脉冲激光沉积法(PLD),以石英玻璃为衬底制备了钽掺杂TiO2薄膜并研究了薄膜样品的光电性质.沉积氧气分气压从0.3Pa变化到0.7Pa时薄膜样品的帯隙变化范围是3.26eV到3.49eV.通过测量电阻率随温度的变化关系确定了薄膜内部的主要导电机理.在150K到210K温度范围内,热激发导电机理是主要的导电机理;而在10K到150K范围内;电导率随温度的变化复合Mott的多级变程跳跃模型(VRH);在210K到300K范围内,电阻率和exp(b/T)1/2呈正比关系.

Tantalum-doped TiO2 thin films were deposited on glass substrates by pulsed laser deposition （PLD）. Their optoelectrical properties were studied. The optical band gap was found varying between 3.26 and 3.49 eV when the oxygen partial pressure increases from 0.3 to 0.7 Pa. The dependence of electrical property of the films on temperature was measured to identify the dominant conduction mechanism. It was found that thermally activated band conduction was the dominant conduction mechanism in the temperatures range of 150 to 210 K. Whereas, in the temperature region of 10 to 150 K, the dependence of the conductivity on temperature followed Mott’s variable range hopping （VRH） model. Moreover, the temperature dependence of resistivity for the films can be described by～exp（b/T）^1/2 at temperatures from 210 to 300 K.