Microwave-induced nonequilibrium temperature in a suspended carbon nanotube

Abstract

Antenna-coupled suspended single carbon nanotubes exposed to 108 GHz microwave radiation are shown to be selectively heated with respect to their metal contacts. This leads to an increase in the conductance as well as to the development of a power-dependent DC voltage. The increased conductance stems from the temperature dependence of tunneling into a one-dimensional electron system. The DC voltage is interpreted as a thermovoltage, due to the increased temperature of the electron liquid compared to the equilibrium temperature in the leads.The temperature response of carbon nanotubes exposed to microwave and terahertz radiation is of great interest both from a practical and a fundamental point of view. One of the many potential applications of carbon nanotubes lies in their response to far-infrared radiation. The bolometric response of either bundles or films of carbon nanotubes has been shown in the far-to mid-infrared range. 1,2 Recently the bolometric and rectifying response of a single carbon nanotube was studied at 77 K and at 4.2 K. 3 Also, detectors based on thermoelectric properties of suspended films of carbon nanotubes have been proposed for the terahertz range and have been demonstrated to work at optical frequencies. 4 The unique one-dimensional electronic states of carbon nanotubes play an important role in the description of their DC electrical response. 5 Due to the strong interactions between the electrons, the response is a collective effect of the entire electron system, as expressed in the Tomonaga-Luttinger-liquid theory. 6 In this theory, these interactions induce a reduced tunneling density of states around the Fermi energy, which leads to a power-law scaling of the conductance with bias voltage and temperature. [7][8][9][10] In studying transport through a carbon nanotube, an important consideration is the energy relaxation. In recent experimental work, indications of weak energy relaxation were reported. 11 In subsequent theoretical work, the intrinsic relation between weak energy relaxation and one-dimensional physics was emphasized. 12,13 It is to be expected that the conductivity of a carbon nanotube will also depend on this weak energy relaxation, when exposed to radiation.In previous work, carbon nanotubes in direct contact with a substrate were studied. This contact leads to interaction with charges in surface dielectrics, an increase in the scattering probability, and phonon-exchange with the substrate. 14-16 In order to avoid these potential complications and increase the thermal response, we have developed suspended carbon nanotubes in broadband antennas. We describe the realization of these suspended carbon nanotubes and their response to 108 GHz radiation. Two main effects are observed and analyzed: the

Carbon-based terahertz devices

“…The S of a CNT film is usually less than ~50 µV/K, but it could be largely enhanced through electronic type separation or the incorporation of other polymers; [24,25] it also can be conveniently turned from p-to n-type by diverse doping methods, [26] allowing for the fabrication of a CNT-PTE detector based on a p-n junction. [7,22,23] THz detectors using antennas coupled to CNT quantum dots, individual metallic SWCNTs, and CNT bundles and films have been demonstrated, [27][28][29][30] but they work only at low temperatures. Here, we demonstrate a roomtemperature-operating, antenna-free, and broadband THz-PTE detector based on aligned SWCNT thin films.…”

Investigation of Rapid Low-Power Microwave-Induction Heating Scheme on the Cross-Linking Process of the Poly(4-vinylphenol) for the Gate Insulator of Pentacene-Based Thin-Film Transistors

“…Traditional microwave annealing is known to be effective for heating because of its advantages including a rapid heating process, shortened manufacturing period, damage-free process and low thermal budget [ 18 , 19 ]. In the reported papers, microwave annealing schemes were always used for heating the semiconductor film because some materials cannot absorb the microwave energy, such as insulators.…”

“…Therefore, materials heated by using microwave radiation will be limited by the selective-heating characteristic of microwaves. In addition, the high microwave power was also a serious issue, leading to a trade-off between fabrication cost and device performance [ 18 , 19 , 20 , 21 ]. In a previous study [ 22 ], a Microwave-Induction Heating (MIH) scheme was proposed for the PVP gate insulator cross-linking process to replace the traditional oven heating process.…”

Poly(4-vinylphenol) gate insulator with cross-linking using a rapid low-power microwave induction heating scheme for organic thin-film-transistors

“…[18][19][20] In previous study, 18 the microwave annealing scheme was usually used for semiconductor annealing (e.g., Silicon, IGZO, ZnO, etc.). Because, using microwave irradiation for heating is limited by its selective-heating characteristic that the energy cannot be absorbed by some materials, such as insulators.…”