Fabrication of semi-conductor titanium oxide films containing isolated fine iron-based metal particles and measurement of the GMR effect under illumination of UV light

本研究的目的是制备一种新型的功能二氧化钛薄膜，它含有孤立的细小的铁颗粒，具有GMR(巨磁电阻)效应，并证实这种纳米复合薄膜在紫外光照射下具有增强GMR效应的作用。通过对本研究中所用的溅射室的改进，以氧化钛和铁片为靶材，制备了由孤立的细小铁粒子组成的纳米复合薄膜。研究了薄膜的晶体结构、光学透过率、电阻、磁性能，包括磁场下的巨磁电阻效应，并考察了制备条件如沉积条件和热处理条件等。主要溅射条件：输入功率50~70W，溅射气体压力3~6×10~(-3)；通过测量沉积时间来手动控制铁颗粒的沉积。然而，在这项研究中，…此外，几个意想不到的机器故障，包括溅射过程中不稳定的溅射气体流量和抽气速度，推迟了原计划。主要研究结果如下：(1)由分散在基体中的孤立铁粉组成的复合薄膜在沉积后表现为非晶态，而在空气中经200℃热处理后则变为氧化钛的晶态。(2)有些薄膜在室温下只有很小的巨磁电阻，ΔR/R=0.02%，并且随着铁粒子总沉积量的增加，薄膜的透明度降低，因此这种薄膜没有巨磁电阻。(3)400℃空气中退火后，由于锐钛矿型钛中的铁颗粒被氧化，金属光亮的薄膜变得透明且呈黄色。然而，这些电影没有显示任何GMR。X射线分析没有证实铁氧化物的存在。(4)透明度、电阻和磁性能之间的关系对于测量所制备的薄膜的磁阻是重要的；光学透明薄膜被证明是不可能测量磁阻的，并且不提供GMR效应。这也证明了良好的制备控制对于获得最佳的纳米复合薄膜在可测量的巨磁电阻范围内是非常重要的。在对目前的实验失败进行了几次改进之后，我们将尝试通过各种制备工艺来增强紫外光照射下的GMR效应，包括溅射Ar和氮气的混合比例。较少

The objects of this research are to fabricate new functional titanium oxide films containing isolated fine iron particles which show the GMR (giant magnetic resistance) effect, and to confirm that such nanocomposite films provide enhancement of the GMR effect under illumination of UV light. After several improvements of the sputtering chamber used in this study, nanocomposite films composed of isolated fine iron particles in the matrix titanium oxide were fabricated by using titanium oxide plate and iron plate as a target. The crystal structure, optical transparency, electrical resistance, magnetic properties including the GMR effect under a magnetic field were examined with reference to preparation conditions such as deposition conditions and annealing conditions. Main sputtering conditions : in-put electric power ; 50〜70W, sputtering Ar gas pressure ; 3〜6 x10^<-3> Torr. The deposition of iron particles was manually controlled by measuring deposition time. During this study, however, … More several unexpected machine troubles including unstable sputtering argon gas flow during sputtering and pumping rate delayed the original plan. The main results are : (1) Composite films composed of isolated fine iron particles dispersed in the matrix titanium oxide showed amorphous state after deposition, but after 200℃ annealing in air they became crystalline state of titanium oxide. (2) Some films provided a very small GMR, ΔR/R=0.02%, at room, and the transparency of the films decreased with increasing total deposition amount of iron particles and thus such films did not show any GMR. (3) After 400℃ annealing in air, the films showing metallic brightness became transparent and yellow-like, probably because of oxidization of iron particles in the anatase-type matrix titanium. The films, however, did not show any GMR. X-ray analysis did not confirm the existence of iron oxides. (4) A relationship among transparency, resistance and magnetic property was found to be important for measuring the magnetoresistance of fabricated films ; Optically transparent films proved to be impossible to measure the magnetoresistance and provided no GMR effect. It also proved that the well-controlled fabrication is very important to get optimum nanocomposite films which are in a measurable range of the GMR. After several improvements of the present experimental failures, we will try to enhance the GMR effect under illumination of UV light through various fabrication processes including a mixture ratio of sputtering Ar and N2 gases. Less