Abstracts Category : Other

Study on the electrical properties of single- and multi-layer graphene nanoribbons for next generation nanoelectronics :

by Reetu Pandey

Graphene nanoribbon (GNR) is a narrow strip of carbon atoms which has exceptional properties and are being exploited for various applications, such as in semiconductor electronics, solar cells, and sensors. However, the realization of GNR based devices still needs an extensive research to achieve the commercial specifications. This research is mainly emphasized on the synthesis of high-quality GNR from double-walled carbon nanotubes (DWNTs) and fabrication of field effect transistor (FET) devices. Moreover, the electrical transport properties were also investigated for single-layer GNR (sGNR), multi-layer GNR with and without adsorption of molecular nanoparticles. The electrical transport properties of GNR device was tuned to semiconducting with the adsorption of molecular nanoparticles. This study demonstrates a simple and fast approach to band gap formation in sGNR using Hexaazatriphenylenehexacarbonitrile (HAT-CN6). In this process, sGNRs were synthesized by unzipping of DWNTs followed by casting the solution of HAT-CN6. HAT-CN6 on GNR forms self-assembled nanoparticle and the adsorption of nanoparticles was confirmed by AFM observation. Further, the electric property of pristine sGNR device and the device with HAT-CN6 were measured using point-contact current imaging (PCI-) AFM and also with the FET device. Thus, the adsorbed nanoparticles on sGNR forms the electron trapping sites which result in a necklike structure of sGNR near the adsorbed region of the molecular nanoparticle. The neck region working similar to narrow width GNR (< 10 nm) allows the charge carriers passing through. Such a narrow sGNR has lateral confinement of charge carrier around the neck region hence the device turns to semiconducting. The activation energy of pristine sGNR and the sGNR with HAT-CN6 were calculated by the results of temperature change measurement as about 1.5 meV and 52 meV, respectively. The pristine sGNR has very low activation energy as compared to the device with HAT-CN6. Thus, the device with HAT-CN6 has a large transition from semimetallic to semiconducting property. The device could have various possible application in future electronics industry due to its semiconducting property. Moreover, the study also explains the fabrication of multi-layer GNR (mGNR) field effect transistor (FET) and control of its electrical property with the adsorption of the flat molecular nanoparticle. The stacked mGNR device shows the similar performance to the sGNR device due to lower inter layer coupling. Inter layer interaction was supposed to be lower since the turbostratic stacking of GNR was formed with CVD growth process. Next, HAT-CN6 were casted on the mGNR device to alter the electronic property of GNR. Thus, the adsorbed nanoparticles form the charge carrier trapping sites on mGNR and the channel width was narrowed due to the nanoparticles on GNR. Hence, the charge carriers are confined in a narrow channel and the device is in a transition state from semimetallic to semiconducting, which is similar to narrow width GNR. The on/offAdvisors/Committee Members: , .