基底温度对直流溅射Nb掺杂TiO_2薄膜性能的影响

Influence of the Substrate Temperature on the Properties of Nb-doped TiO_2 Films Deposited by DC Magnetron Sputtering

采用陶瓷靶直流磁控溅射,以玻璃为基底制备2.5wt%Nb掺杂TiO2薄膜,控制薄膜厚度在300~350 nm,研究了不同基底温度下所制得薄膜的结构、形貌和光学特性.XRD分析表明,基底温度为150℃、250℃和350℃时,薄膜分别为非晶态、锐钛矿（101）和金红石相（110）结构.基底温度250℃时,锐钛矿相薄膜的晶粒尺寸最大,约为32 nm.薄膜表面形貌的SEM分析显示,薄膜粗糙度和致密度随基底温度升高得到改善.薄膜的平均可见光透过率在基底温度为250℃以内约为70%,随基底温度升高至350℃,平均透过率下降为59%,金红石相的存在不利于可见光透过.Nb掺杂TiO2薄膜的光学带宽在3.68~3.78 eV之间变化.基底温度为250℃时,锐钛矿相薄膜的禁带宽度最大,为3.78 eV.

Nb-doped （2.5wt%） TiO2 thin films was deposited on glass substrate by DC magnetron sputtering from a ceramic target and the films thickness was controlled in the range from 300 nm to 350 nm. The structure, surface morphology and optical properties of the films deposited at different substrate temperatures were investigated by X-ray diffraction, scanning electron microscope, and optical transmission spectroscope. The films deposited at 150℃, 250℃ and 350℃ were amorphous, anatase and ruffle, respectively. The grain size of the typical anatase film deposited at 250℃ reached the maximum of 32 nm. The roughness of the films decreased and their density increased with the rising of substrate temperature. The average optical transmittance of films were around 70% when the substrate temperatures were below 250℃. As the substrate temperature were risen to 350℃, the films＇ transmittance dropped to 59%. It indicated that the transmittance of visible light was hindered by the futile phase in the Nd-doped TiO2 films. The optical band gap of the films were in the range from 3.68 eV to 3.78 eV, and the optical band gap of the typical anatase film deposited at 250℃ reached the highest value of 3.78 eV.