C掺杂TiO薄膜的制备及其第一性原理研究

Deposition and first-principles caculation of carbon-doped titanium monoxide films

TiO在微电子结构器件中有重要的应用前景.本文以CO2作反应气体,采用直流反应磁控溅射方法成功制备出C掺杂TiO薄膜.采用XRD,XPS和四探针电阻计对薄膜结构、成分和电阻率进行表征.在实验结果的基础之上建立起TiO和C掺杂TiO的计算模型并采用第一性原理方法计算其能带结构和电子态密度.实验结果表明薄膜相结构为面心立方的岩盐结构,C取代O的阴离子掺杂为主要掺杂方式,薄膜电阻率为52.2μ·cm.第一性原理计算结果表明,费米能级穿过TiO的导带,TiO具有金属性导电的能带结构特征;C掺杂TiO后,其金属性导电的能带结构没有改变,只是在费米面附近出现C 2p态提供的杂质能级,杂质能级扩展了TiO的导带宽度并提高了费米面附近的电子能态密度,从而导至TiO电导增加,电阻率降低.第一性原理计算结果与实验结果一致.

Carbon-doped titanium monoxide films were successfully fabricated using CO2 as reactive gas by means of DC reactive magnetron sputtering. Phase tructure, composition and resistivity of the fabricated films were investigated by using X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and four point probe method. Results show that the fabricated film has a cubic phase structure, and the carbon element exists mainly as anion in the lattice of C-TiO. The resistivity of C-TiO is 52.2 μ？·cm which is lower than that of pure TiO. Results of first principles calculation show that the Fermi levels of both TiO and C-TiO lie in their conduction bands, thus TiO and C-TiO have characteristics of metal conduction. Also the results of first principles calculation show that impurity levels of C 2p lie near the conduction band of C-TiO, which extend the width of conduction band and increase the density of states near the Fermi level of C-TiO, so the conductivity of C-TiO is larger than that of undoped TiO. The theoretical calculations are in agreement with experiment results.