Dolafi Rezaee Melorina, Dahal Biplav, Watt John, Abrar Mahir, Hodges Deidra R, Li Wenzhi
Department of Physics, Florida International University, Miami, FL 33199, USA.
Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
Nanomaterials (Basel). 2024 Jun 2;14(11):965. doi: 10.3390/nano14110965.
Single-walled carbon nanotube (SWCNT) thin films were synthesized by using a floating catalyst chemical vapor deposition (FCCVD) method with a low flow rate (200 sccm) of mixed gases (Ar and H). SWCNT thin films with different thicknesses can be prepared by controlling the collection time of the SWCNTs on membrane filters. Transmission electron microscopy (TEM) showed that the SWCNTs formed bundles and that they had an average diameter of 1.46 nm. The Raman spectra of the SWCNT films suggested that the synthesized SWCNTs were very well crystallized. Although the electrical properties of SWCNTs have been widely studied so far, the Hall effect of SWCNTs has not been fully studied to explore the electrical characteristics of SWCNT thin films. In this research, Hall effect measurements have been performed to investigate the important electrical characteristics of SWCNTs, such as their carrier mobility, carrier density, Hall coefficient, conductivity, and sheet resistance. The samples with transmittance between 95 and 43% showed a high carrier density of 10-10 cm. The SWCNTs were also treated using Brønsted acids (HCl, HNO, HSO) to enhance their electrical properties. After the acid treatments, the samples maintained their p-type nature. The carrier mobility and conductivity increased, and the sheet resistance decreased for all treated samples. The highest mobility of 1.5 cm/Vs was obtained with the sulfuric acid treatment at 80 °C, while the highest conductivity (30,720 S/m) and lowest sheet resistance (43 ohm/square) were achieved with the nitric acid treatment at room temperature. Different functional groups were identified in our synthesized SWCNTs before and after the acid treatments using Fourier-Transform Infrared Spectroscopy (FTIR).
采用浮动催化化学气相沉积（FCCVD）法，以低流速（200 sccm）的混合气体（氩气和氢气）合成了单壁碳纳米管（SWCNT）薄膜。通过控制碳纳米管在膜滤器上的收集时间，可以制备不同厚度的碳纳米管薄膜。透射电子显微镜（TEM）显示，碳纳米管形成了管束，平均直径为1.46纳米。碳纳米管薄膜的拉曼光谱表明，合成的碳纳米管结晶良好。尽管到目前为止已经对碳纳米管的电学性质进行了广泛研究，但尚未充分研究碳纳米管的霍尔效应以探索碳纳米管薄膜的电学特性。在本研究中，进行了霍尔效应测量以研究碳纳米管的重要电学特性，如载流子迁移率、载流子密度、霍尔系数、电导率和薄层电阻。透光率在95%至43%之间的样品显示出10¹⁰ cm⁻³的高载流子密度。还使用布朗斯特酸（盐酸、硝酸、硫酸）对碳纳米管进行处理以增强其电学性质。酸处理后，样品保持其p型性质。所有处理过的样品的载流子迁移率和电导率增加，薄层电阻降低。在80°C下用硫酸处理获得了最高迁移率1.5 cm²/Vs，而在室温下用硝酸处理获得了最高电导率（30720 S/m）和最低薄层电阻（43欧姆/平方）。使用傅里叶变换红外光谱（FTIR）在酸处理前后的合成碳纳米管中鉴定出不同的官能团。
