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磁控溅射制备氮化铜薄膜及其掺杂研究

Preparation and Characterization of Doped Cu3N Thin Films by Magnetron Sputtering

【作者】 白秋飞

【导师】 李兴鳌;

【作者基本信息】 南京邮电大学 , 光学, 2012, 硕士

【摘要】 Cu3N薄膜是一种以共价键结合的亚稳态半导体材料,具有热分解温度低、电阻率高、在红外和可见光波段反射率低等特点,成为近年来光存储和微电子半导体等领域中备受瞩目的新型应用材料。Cu3N晶体为反三氧化铼(anti-ReO3)型简立方结构,由于Cu原子并未占据Cu3N晶胞的体心位置,其它原子填充到其体心空位,将引起薄膜光学和电学性质的显著变化。本论文采用反应直流磁控溅射法在不同氮气流量下制备了Cu3N薄膜,采用磁控双靶反应共溅射法制备了Ni掺杂的Cu3N薄膜。用XRD、EDS、SEM、UV-VIS、表面轮廓仪、四探针和显微硬度仪等现代材料分析技术,研究了氮气流量和Ni掺杂对Cu3N薄膜结构和性能的影响。结果表明:(1)氮气流量的改变影响了Cu3N薄膜的晶体结构和择优生长取向。当氮气流量增高时,薄膜由Cu3N (111)晶面择优生长转变为(100)面择优生长;薄膜的沉积速率在氮气流量为15sccm时有极大值,电阻率随流量的增长呈U型变化,显微硬度也受到一定影响。实验表明,5~10sccm的氮气流量是生长良好择优取向Cu3N薄膜的最适宜流量条件。(2)Ni的掺入并未影响Cu3N薄膜晶体结构和沿(111)晶面的择优生长,但使(111)衍射峰强度减弱,并向小角度偏移,薄膜晶格常数和晶粒尺寸变大、表面形貌更为粗糙,Ni的过量掺杂会导致薄膜无法形成Cu3N相。紫外-可见反射谱表明,Ni的掺杂使薄膜在红外和可见光区域的反射率显著降低,与热分解后的铜镍合金膜有较大差异,显示出作为光存储材料的良好性质。此外,薄膜的电阻率也随Ni的掺入而迅速减小,实现从半导体向导体的过渡。

【Abstract】 Copper nitride thin film (Cu3N) is a metastable semiconducting material,which is formed through the covalent bonding between Cu and N atoms. With the low decomposition temperature, high resistivity and reflectance of infrared and visible band, Cu3N has been attracting considerable attention as a new material applicable in optical storage and microelectronics. Moreover, Cu3N is also an excellent host structure since it has the cubic anti-ReO3 structure in which Cu atoms do not occupy the body center of the cubic unit cell, such that an additional atom can be inserted into the body center. This will cause remarkable changes in optical and electrical properties of this material.In this paper, Cu3N films were deposited by reactive DC magnetron sputtering at various N2-gas flow rates, Cu3NixN films were prepared by co-sputtering of Ni and Cu targets. The films were characterized by XRD, EDS, SEM, UV-VIS, Profilometer, Four-probe and Microhardness Tester. From the experimental values, we studied the effects of doping Ni and N2-gas flow rates on the structure and properties of Cu3N films, the conclusions which have been made are as follows:(1) The N2-gas flow rate affects the crystal structure and the preferred orientation of Cu3N films. The deposited films prefer to being (111)-oriented at low N2-gas flow rate but (100)-oriented at high one. The deposition rate of the films got a maximum when the N2-gas flow rate was 15sccm. With the increasing of N2-gas flow rate, the resistivity increased and then decreased, the microhardness was also affected. The optimum N2-gas flow rate for producing high-quality and well-oriented Cu3N films are 5~10sccm in this system.(2) The addition of Ni to Cu3N films does not modify the film crystal structure and the preferred orientation, but the intensity of diffraction peak (111) reduced, and the position shifted a little angle with the contents of Ni to Cu3N films increased, as also as the larger of the lattice constant. The Cu3N phase disappeared when the contents of Ni excess. Furthermore, of infrared and visible, the alloy film of Cu and Ni obtained by the thermal decomposition showed a large difference in reflectance, which is applicable to the optical recording media. The electrical resistivity decreased greatly when the contents of Ni to Cu3N films increased, which have made the films changed from semiconductor to conductor.

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