【作者】 李响；

【导师】 刘技文； 安玉凯；

【作者基本信息】 天津理工大学 ， 材料物理与化学， 2011， 硕士

【摘要】 信息时代的到来,对信息的处理、传输和存储的一体化提出了更高的要求,人们期望得到稀磁半导体为代表的自旋电子器件以满足要求。SiC稀磁半导体既具有优良的半导体性能又有磁性,是潜在自旋电子器件的优良材料,受到了人们广泛的关注。采用射频磁控溅射共溅射法,制备Mn、Co掺杂的SiC稀磁半导体薄膜。薄膜在4×10^-4Pa条件下进行1200℃、800℃,1h的退火处理。薄膜厚度约400nm。采用X射线衍射仪（XRD）、扫描电子显微镜（SEM）、X射线光电子能谱（XPS）和X射线吸收精细结构技术（XAFS）对薄膜进行表征,通过多功能物理测试系统（PPMS）和荧光光谱仪对薄膜的磁性和光致发光特性进行测试,通过R-T、I-V曲线对薄膜的半导体输运特性进行研究。结果如下:1、Mn、Co掺杂SiC薄膜在2θ=35.8o处存在衍射峰,这个衍射峰位为3C-SiC的第一强峰,说明薄膜的晶体结构为3C-SiC。Mn、Co的掺杂使SiC晶格发生畸变,SiC衍射峰半高宽增大。随着掺杂浓度的升高,衍射峰从高角度向低角度移动。经过1200℃退火的薄膜,出现了Mn4Si7、CoSi第二相化合物。2、经XPS,XAFS表征,对于制备态的SiC薄膜和退火后的SiC薄膜,Mn、Co均以离子态掺入薄膜中,且均为+2价。经分析,Mn、Co是以替位形式掺入SiC晶格。退火后的Mn、Co掺杂SiC薄膜Si 2p的XPS图谱中也发现了Mn-Si键和Co-Si键,与XRD表征出薄膜中存在第二相的结果相一致,进一步印证了Mn₄Si₇、CoSi第二相化合物的存在。3、Mn、Co掺杂SiC薄膜的I-V曲线为线性关系,Mn、Co的掺杂没有形成金属—绝缘颗粒薄膜,证明薄膜中不存在金属团簇,形成的是非均匀体系的薄膜。R-T曲线测试表明,Mn、Co掺杂后,SiC薄膜的电阻率随温度的升高而降低,证明SiC薄膜仍具有半导体属性。4、磁性测量表明,Mn、Co掺杂SiC薄膜都具有室温铁磁性。在制备态的Mn掺杂SiC薄膜中,随着Mn掺杂量增加,饱和磁化强度有明显增加,当掺杂量达到9at%时,薄膜的饱和磁化强度接近15emu/cm³,随着退火温度升高,薄膜的饱和磁化强度也随之升高。在Co掺杂的薄膜中,随着掺杂量升高,薄膜的饱和磁化强度从1.9emu/cm³升到6.5 emu/cm³,当掺杂量达到10at%后,薄膜的饱和磁化强度又降到2emu/cm³。在不同退火温度薄膜的比较中发现,800℃退火的Co掺杂SiC薄膜饱和磁化强度最强,达12emu/cm³。更多还原

【Abstract】 With the coming of information age,the higher demands for information processing and transmission and storage of integration are more and more increased.The Diluted Magnetic Semiconductor on behalf of the spin electronic appliance has been expected. SiC based DMS,with its excellent performance of semiconductor and property of magnetic material concerned by more people.SiC films doped with Manganese（Mn） and Cobalt（Co） were prepared by the RF-magnetron sputtering. The prepared films were annealed in a vacuum environment at 1200℃and 800℃.The annealing treatment time was 40 minutes. The Mn and Co-doped films were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, X-ray photoelectron spectroscopy （XPS） and X-ray absorption fine stucture （XFAS）. The magnetic property and photoluminescence were texted by physical testing systems（PPMS）and UV - visible light photometer.The transport property of the DMS film was studied by R-T and I-V Curves. The results show that:1. There exist a diffraction peak at 2θ=38.319°in the Mn and Co-doped SiC films.The diffraction peak is the strongest diffraction peak of 3C-SiC.So the structure is 3C-SiC lattice structure,the SiC lattice was distortioned by Mn and Co-doping.With the increasing of doping concentration,the diffraction peak moved from high to low angle.After annealing, the second phase Mn₄Si₇ and CoSi formed.2. By XPS and XAFS measurements, it can be found that the Mn and Co atoms were all doped into SiC lattice for the as-deposited and annealed SiC films, they were all two price. Co and Mn atoms were substituted enter the SiC lattice.The Mn-Si and Co-Si key were found in the annealed films.3. The I-V curve shows linear relationship,there were no metal cluster in the films.The metal-insulation films were not formed in Mn and Co-doped films.It shows that the films were un-homogeneous body system.With the temperature increased ,the R-T curve resistivity contours reduced.The semiconducting properties is obvious.4. The magnetic property test shows that Mn and Co-doped films have room temperature ferromagnetic.The saturation magnetization increased with the increasing of Mn content.The saturation magnetization was 15emu/cm³,When the Mn content was 9at%. With the annealing temperature increasing, the saturation magnetization of the film increased. The saturation magnetization increasing with the increasing Co content,from 1.9emu/cm³ to 6.5 emu/cm³ ,When the Mn content was 9at%,the saturation magnetization reduced to 2 emu/cm³ .The 800℃annealing temperature benefitsed to the magnetization of the films.Its saturation magnetization is 12emu/cm³.更多还原