Marlene Bonmann, Microtechnology and Nanoscience - MC2

​Title: Graphene field-effect transistors and devices for advanced high frequency applications
​Marlene is a PhD student at the Terahertz and Millimetre Wave Laboratory
Examiner: Prof. Jan Stake
Main supervisor: Senior Researcher Andrei Vorobiev
New device technologies and materials are continuously explored, in order to increase the bandwidth of high speed electronics, thereby extending the data rate and range of applications. Essential components in those electronic devices are transistors. The 2D material graphene, with its extremely high charge carrier velocity, is considered as a promising new channel material for advanced high frequency field-effect transistors. However, so far, most fabrication processes of graphene field-effect transistors (GFETs) unintentionally introduce impurities and defects at the interface between graphene and adjacent materials, which degrade the device performance. Furthermore, there is a significant increase in the channel temperature caused by self-heating. In this thesis, the influence of impurities and defects on charge transport, the limitations of the saturation velocity, and the effect of velocity saturation and self-heating on the transit frequency (fT) and the maximum frequency of oscillation (fmax) of GFETs are analysed. In addition, GFETs with state-of-the-art extrinsic fT =34 GHz and fmax =37 GHz, and an integrated 200-GHz GFET based receiver are presented. Also, through the development of a fabrication process of GFETs with a buried gate configuration, this work contributed to the direct nanoscopic observation of plasma waves in the GFET channel during terahertz illumination. The presented results allow for outlining paths towards the realisation of GFETs with extrinsic fT and fmax in the sub-terahertz range.

Category Thesis defence
Location: Kollektorn, lecture room, Kemivägen 9, MC2-huset
Starts: 16 January, 2020, 09:00
Ends: 16 January, 2020, 11:00

Published: Wed 22 Jan 2020.