Ti掺杂对Sb_(2)Te_(3)薄膜的结构及光学性质的调控

Regulation on microstructural and optical properties of Sb_(2)Te_(3) films induced by titanium doping

对Sb2Te3薄膜的结构、线性光学及非线性吸收性质的Ti掺杂影响进行了系统性探究。利用磁控溅射和高温退火手段制备了不同Ti掺杂浓度的晶态Sb_(2)Te_(3)薄膜。X射线光电子能谱分析显示Sb_(2)Te_(3)薄膜中的Ti元素以Ti^(4+)化学态以TiTe_(2)的形式存在。线性光学性质结果表明,在保持非线性器件中宽工作波长特性的同时,Ti掺杂可以提高Sb2Te3薄膜的透射率,并降低光学带隙从1.32 eV至1.25 eV,根据Burstein-Moss理论,这取决于载流子的减少。利用自主搭建的开孔Z扫描系统,测试了薄膜样品在132 GW/cm^(2)强度下800 nm飞秒激光激发的非线性吸收性质,结果显示的Ti掺杂引起的饱和吸收可调谐行为可归因于光学带隙减小与晶化抑制的竞争效应。此外,Ti掺杂将Sb2Te3薄膜的激光损伤阈值从188.6 GW/cm^(2)提高到了265.5 GW/cm^(2)。总而言之,Ti掺杂Sb2Te3薄膜在非线性光学器件领域具有广泛的应用前景。

In this work,the doping effects of Ti on the structural,linear optical properties and nonlinear absorp-tion of Sb_(2)Te_(3) thin films were systematically studied.A magnetron sputtering system and an annealing furnace are employed to prepare the crystalline Sb_(2)Te_(3) samples with different doping concentrations of Ti.The X-ray photo-electron spectroscopy analysis confirmed that the Ti element exists in the Sb_(2)Te_(3) films is in the form of TiTe_(2),in which the chemical state of Ti4+arises.For linear optical properties,the results indicate that the Ti dopant can im-prove the transmittance of the Sb_(2)Te_(3)films,when a wide working wavelength is used in the nonlinear devices.The optical band gap decreases from 1.32 eV to 1.25 eV for the Ti-doped Sb_(2)Te_(3) films,which is dependent on the reduction of carriers according to the Burstein-Moss theory.An open-aperture Z-scan system is set up to deter-mine the nonlinear saturated absorption of the film samples,which is excited by an 800 nm femtosecond laser at a power of 132 GW/cm^(2).Moreover,the adjustable behavior caused by Ti doping could be attributed to the competi-tion between the decrease in the optical band gap and the inhibition of the crystallization.Additionally,it is inter-esting to and that the Ti doping improves the laser damage threshold of the Sb_(2)Te_(3) thin films from 188.6 to 265.5GW/cm^(2).In general,the Ti-doped Sb_(2)Te_(3) thin films have wide-ranging application possibilities for the field of nonlinear optical devices.