硅基板上Fe掺杂TiO2氧敏薄膜的制备、结构与性能研究

采用溶胶-凝胶法,以Ti(OC₄H₉)₄为前驱体,用提拉法在硅基板上制备了掺Fe的TiO₂氧敏薄膜,对薄膜物相结构进行了X射线衍射(XRD)测定,利用扫描电镜(SEM)对薄膜微结构进行了观察.结果表明:在硅基板上生长的TiO₂薄膜中锐钛矿相为均匀小晶粒分布结构,金红石相以大尺度团聚结构形貌出现.Fe离子的掺杂对硅基板上制备的TiO₂薄膜中金红石相的形成有很大的影响.Fe的掺入降低了金红石相的形成温度约100℃,Fe掺量在6mol% 时,形成金红石相的量达到最大,即析晶能力最强.薄膜中形成晶相的晶格常数在<6mol%的低Fe范围内,随较小的Fe离子取代较大的Ti离子,锐钛矿相和金红石相的晶格常数都随之减小;在>6mol%的高Fe掺量范围内,随Fe掺量的增加,体系缺陷过量增加,晶格结构畸变严重,伴随着畸变能的释放,金红石相的晶格常数c轴逐渐增长,n轴略有下降(或基本不变). TiO₂氧敏薄膜的氧敏性能受金红石相含量和氧空位浓度控制.当Fe离子掺杂浓度为6mol% 时,金红石相及相应氧空位达到最大值,TiO₂氧敏薄膜的氧敏性能也达到最大值,比刚形成金红石相的薄膜的氧敏性能增加近19倍.

Influence of Fe3+ Doped on Phase Formation and the Oxygen Sensitivity of TiO2 Oxygen Sensitive Thin Films Prepared on Silicon Substrate by Sol-Gel Method

The Fe³⁺ doped TiO₂ oxygen sensitive thin films deposited on single crystal silicon substrates were prepared by a sol-gel method. The phase structure of the thin films was measured by X-ray diffraction (XRD). The morphologies were observed by scanning electron microscope (SEM). The results showed that the anatase phase appeared with a small grain size dispersed homogeneously in the thin film. The rutile phase appeared with a morphology of special clustered grains and large sizes in the thin film. It was exhibited evidently that the formation of the rutile phase in the thin film on a single crystal substrate was dependent on Fe³⁺ doping in the system. The formation temperature was about 100℃ lower with 3mol% Fe³⁺ doped than that without Fe³⁺ doping. The largest content of the rutile phase appeared in the thin film while Fe³⁺ doping of about 6mol%. In addition, the crystal lattice of both the anatas phase and the rutile phase decreased with the substitution of a small size of Fe ions for a large size of Ti ions when doping Fe ions concentrantion below 6mol%. As Fe ions doped was above 6mol%, the c axis of the rutile phase increased while the c axis kept almost constant with the increase of Fe and thus both oxygen vacancy and structure distortion increased. The oxygen sensitivity of Fe doped TiO₂ thin films was controled by the concentration of the oxygen vacancies and the content of the rutile phase in TiO₂ thin films.The rutile phase and the sensitivity in the Fe doped TiO₂ thin film showed maximum while Fe doping was 6mol%, and its oxygen sensitivity was 19 times more than that of the TiO₂ thin film with 3mol% Fe doped.