Improving the Performance of Nanoscale Field-Effect Transistors Through Electrostatic Engineering

The continued scaling of field-effect transistors (FETs) requires that nearly every aspect of these devices be optimized to ensure that they can continue to meet practical performance requirements. However, scaling the channel lengths of FETs naturally enhances electrostatic and quantum mechanical short-channel effects, thereby increasing leakage currents in the OFF-state, reducing driving currents in the ON-state, and making it difficult for FETs attain optimal switching behaviours. To mitigate these detrimental effects, it is imperative to (i) thoroughly understand the electrostatic operation of nanoscale FETs and (ii) establish novel design strategies to mitigate short-channel effects. In this thesis, I address these two challenges by studying the electrostatic operation of nanoscale FETs using simulation techniques. In particular, I use the non-equilibrium Green's function method, an atomistic quantum transport simulation technique, to study the electrostatic operation of MOSFETs and to assess the utility of novel electrostatic design strategies for nanoscale FETs. The body of this thesis is divided into three main works. In the first, I study how individual elements of a metal-oxide-semiconductor FET's (MOSFET's) semiconductor's anisotropic permittivity affect device performance, and I establish electrostatic-based guidelines for selecting optimal semiconductors for future MOSFETs. Next, I study how replacing an FET's conventional isotropic insulators (i.e. gate insulator and spacers) with anisotropic insulators can improve the performance of both conventional MOSFETs and tunnel FETs, and I propose novel insulator architectures to further optimize the performance of these devices. Finally, in my third study, I examine how fringe-induced barrier lowering, an electrostatic short-channel effect created by implementing high-κ gate insulators, can be exploited to suppress quantum mechanical short-channel effects (source-to-drain tunneling) to improve the overall performance of nanoscale MOSFETs. The operating principles and design rules established in these three works extend the current picture of the electrostatic operation and design rules for nanoscale FETs to help device designers continue to scale FETs while meeting essential performance benchmarks

Two-Dimensional Electronics - Prospects and Challenges

During the past 10 years, two-dimensional materials have found incredible attention in the scientific community. The first two-dimensional material studied in detail was graphene, and many groups explored its potential for electronic applications. Meanwhile, researchers have extended their work to two-dimensional materials beyond graphene. At present, several hundred of these materials are known and part of them is considered to be useful for electronic applications. Rapid progress has been made in research concerning two-dimensional electronics, and a variety of transistors of different two-dimensional materials, including graphene, transition metal dichalcogenides, e.g., MoS2 and WS2, and phosphorene, have been reported. Other areas where two-dimensional materials are considered promising are sensors, transparent electrodes, or displays, to name just a few. This Special Issue of Electronics is devoted to all aspects of two-dimensional materials for electronic applications, including material preparation and analysis, device fabrication and characterization, device physics, modeling and simulation, and circuits. The devices of interest include, but are not limited to transistors (both field-effect transistors and alternative transistor concepts), sensors, optoelectronics devices, MEMS and NEMS, and displays

Electronic Nanodevices

The start of high-volume production of field-effect transistors with a feature size below 100 nm at the end of the 20th century signaled the transition from microelectronics to nanoelectronics. Since then, downscaling in the semiconductor industry has continued until the recent development of sub-10 nm technologies. The new phenomena and issues as well as the technological challenges of the fabrication and manipulation at the nanoscale have spurred an intense theoretical and experimental research activity. New device structures, operating principles, materials, and measurement techniques have emerged, and new approaches to electronic transport and device modeling have become necessary. Examples are the introduction of vertical MOSFETs in addition to the planar ones to enable the multi-gate approach as well as the development of new tunneling, high-electron mobility, and single-electron devices. The search for new materials such as nanowires, nanotubes, and 2D materials for the transistor channel, dielectrics, and interconnects has been part of the process. New electronic devices, often consisting of nanoscale heterojunctions, have been developed for light emission, transmission, and detection in optoelectronic and photonic systems, as well for new chemical, biological, and environmental sensors. This Special Issue focuses on the design, fabrication, modeling, and demonstration of nanodevices for electronic, optoelectronic, and sensing applications

Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems

We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.Peer ReviewedPostprint (published version

Proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress

Published proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress, hosted by York University, 27-30 May 2018