沉积氧压对RuVO2合金薄膜结构及MIT特性的影响研究

Effect of deposition oxygen pressure on the structure and MIT characteristics of RuVO 2 alloy thin films

本工作采用脉冲激光沉积法,以c-Al2O3为衬底,金属钌(Ru)镶嵌金属钒(V)圆片作为靶材,高纯氧气为反应气体,在不同沉积氧压下制备出一系列RuVO2合金薄膜.采用XRD、XPS、紫外-可见-近红外光谱仪、四探针测试仪等表征了薄膜的结构、成分及光电性能.实验结果表明:在不同沉积氧压下,薄膜均沿(010)晶面高度取向生长,薄膜的摇摆曲线半高宽在0.050°~0.091°之间,薄膜具有良好的结晶质量.低氧压(1.5 Pa)下制备的RuVO2薄膜成分严重偏离化学计量比而含有大量O空位缺陷.随着沉积氧压增大,薄膜化学成分接近化学计量比2∶1;在大于2.4 Pa氧压条件下制备的薄膜都表现出显著的MIT特性,薄膜相变温度在50~55℃之间,在相变前后电阻率发生3个数量级的突变,同时对红外光展现出良好的调制能力,最高可达17%.氧压太高将降低薄膜沉积速率而不利于薄膜生长.

In this work,series of RuVO2 alloy films were prepared by pulse laser deposition on c-Al2O3 substrates using a ruthenium(Ru)inlaid metal vanadium(V)target under different pressures of high-purity oxygen.XRD,XPS,UV-Vis-NIR spectroscopy and four-probe testers were used to characterize the structure,composition,and optoelectronic properties of these films.The results show that these films are highly oriented along the(010)crystal plane with the full width at half maximum of rocking curves in the range of 0.050°-0.091°,indicating a high crystal quality of the films.The composition of RuVO2 film prepared under low oxygen pressure(1.5 Pa)deviates severely from the stoichiometry and contains a lot of O vacancy defects.As the oxygen pressure increases,the composition of the films approaches the stoichiometric ratio of 2∶1,and all the films prepared under oxygen pressures above 2.4 Pa show significant MIT characteristics.The phase transition temperatures of these films varies from 50 to 55℃,and the resistivity changes by three orders of magnitude before and after the phase transition.At the same time,the films show high modulation ability for infrared light up to 17%.If the oxygen pressure is too high,the film deposition process is degraded with a reduced growth rate.