Characterization of Undoped, N- and P-Type Hydrogenated Nanocrystalline Silicon Carbide Films Deposited by Hot-Wire Chemical Vapor Deposition at Low Temperatures
Characterization of Undoped, N- and P-Type Hydrogenated Nanocrystalline Silicon Carbide Films Deposited by Hot-Wire Chemical Vapor Deposition at Low Temperatures
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DOI：
10.1143/jjap.46.1415
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发表时间：
2007-04
影响因子：
1.5
通讯作者：
S. Miyajima;A. Yamada;M. Konagai
中科院分区：
文献类型：
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作者：
S. Miyajima;A. Yamada;M. Konagai
采用热丝化学气相沉积法在玻璃和硅衬底上成功地沉积了n型和p型氢化纳米晶立方碳化硅（nc-3C-SiC：H）薄膜。通过X射线衍射（XRD）、傅里叶变换红外吸收光谱（FTIR）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）、椭圆偏振光谱仪、光热偏转光谱（PDS）和电导率测量等手段对薄膜的结构、光学和电学性能进行了研究。XRD和FTIR测试结果表明，薄膜的平均晶粒尺寸与SiC伸缩模振动宽度之间存在明显的相关性。随着晶粒尺寸从6.4 nm增加到16.6 nm，薄膜的暗电导率从5.8×10-11增加到6.2×10- 6S/cm。对暗电导率的详细分析表明，费米能级位置受薄膜晶粒尺寸的影响。椭圆偏振光谱测量表明，薄膜的介电函数的强烈影响的晶粒尺寸。使用磷化氢、六甲基二硅氮烷和二甲基氢化铝作为掺杂剂，也成功地沉积了n型和p型nc-3C-SiC：H薄膜。n型和p型薄膜的暗电导率分别达到5.32×10-0和7.67×10- 4S/cm。掺杂薄膜的光学吸收光谱表明，p型掺杂显着影响nc-3C-SiC：H的带隙以上的吸收系数相比，n型掺杂。对于n型膜，带隙以下的吸收系数受自由载流子吸收以及带隙内的局域态的影响。
Undoped, n- and p-type hydrogenated nanocrystalline cubic silicon carbide (nc-3C–SiC:H) films were successfully deposited on glass and silicon substrates at a low substrate temperature of about 300 °C by hot-wire chemical vapor deposition. The structural, optical, and electrical properties of the films were investigated by X-ray diffraction (XRD), Fourier transform infrared absorption (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry, photothermal deflection spectroscopy (PDS), and conductivity measurements. The XRD and FTIR measurements revealed a clear correlation between the average grain size and width of the SiC stretching mode vibration of the films. The dark conductivity of the films was increased from 5.8×10-11 to 6.2×10-6 S/cm with increasing the grain size from 6.4 to 16.6 nm. The detailed analysis of the dark conductivity indicates that the Fermi level position is affected by the grain size of the films. Spectroscopic ellipsometry measurements showed that the dielectric functions of the films are strongly affected by the grain size. The n- and p-type nc-3C–SiC:H films were also successfully deposited using phosphine, hexamethyldisilazane, and dimethylaluminumhydride as dopants. For the n- and p-type films, the dark conductivities of 5.32×10-0 and 7.67×10-4 S/cm were achieved, respectively. The optical absorption spectra of the doped films indicate that p-type doping significantly affects absorption coefficients above the bandgap of nc-3C–SiC:H compared with n-type doping. For the n-type films, the absorption coefficients below the bandgap are affected by free carrier absorption as well as by localized states within the bandgap.