Abstract
In this work, we discover that single-walled carbon nanotubes (SWNTs) exhibit exceptionally high quality factor in ac circuit. We find that SWNTs not only play the role as a dielectric material to contribute the capacitance to an ac circuit, but also contribute the inductance to the circuit due to the helical current arisen in itself. For the contribution of SWNTs, the circuit performs extra high quality factor compared to traditional material. In the end of this chapter, we will discuss the electrical behavior and the main mechanism of SWNTs in a RLC circuit. In addition, we illuminate the SWNTs device by laser in order to find the relationship between the photocurrent and the electrical characteristics. When the device illuminate by laser, the resistance decreases and the quality factor increase as well. In addition to the quality factor, the resonant frequency is also changed after illuminating.