Fabrication and characterisation of CVD-graphene nanoribbon single electron transistors

• Main Author: Reynolds, Jamie Dean
• Other Authors: Tsuchiya, Yoshishige
• Published: University of Southampton 2018
• Subjects: 621.38
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.741717

Graphene was the first 2 dimensional material discovered and rapidly received a lot of attention because of its astounding properties. It is still the highest conductivity material recorded and very robust despite its single atomic layer thickness. However a key issue with graphene has been that it is a semimetal and not a semiconductor, so it lacks a band gap. Originally a large amount of focus was on researching methods to overcome this issue for logic devices. At first the patterning into nanoribbons was seen as a method to achieve this, but the fabrication of a nanoribbon came at a cost of graphene’s high mobility electrons. From conducting this research an interesting property of graphene emerged. It was capable of acting intrinsically as a single electron transistor, enabling a different type of more than Moore device to be fabricated that can be used in future nanoelectronic applications. The aim of this project has been to investigate the transport properties of polycrystalline graphene grown using chemical vapour deposition. The use of polycrystalline graphene enables the fabrication of wafer scale devices that can be stacked on a large variety of surfaces. So far though there has been a lack of investigation into the scaling effects of polycrystalline graphene nanoribbons and the single electron tunnelling properties associated with them. This work presents the first detailed investigation into their properties and shows that polycrystalline graphene can be used for producing high quality single electron transistors. Nanoribbons are fabricated down to sub 20 nm widths with high aspect ratio transitions from wide to narrow segments. The single electron transistor has demonstrated a single quantum dot impacted by the effect of energy level spacing.