Two-Dimensional Materials and Devices | PhD Oral Defense, Stanford University, June 2018.

Over the past five decades, thanks to Moore’s law, we have enjoyed an exponential increase in the performance and reduction in the cost of semiconductor technology. However, as individual device dimensions reach below ~10 nm, transistors made from traditional materials such as silicon (Si) are prone to increased leakage and other non-ideal effects. Moreover, Si transistors are proving difficult to integrate into 3-dimensional (3D) circuits which would provide substantial energy and delay improvements. Instead, 2-dimensional (2D) semiconductors such as MoS2 hold unique advantages due to their three-atom thickness, lack of dangling bonds, and better potential for 3D integration.
To understand the physics of 2D devices and their applications, we use a multiscale atom to system simulation approach including first principles calculations, ab initio and molecular dynamics, TCAD, and compact modeling. Based on Landauer’s approach, we uncover fundamental limits of electrical and thermal interfaces to 2D semiconductors. These are particularly important, and 2D transistors can be thought of as the extreme, atomically-thin limit of silicon-on-insulator (SOI) technology. With the help of atomistic simulations, we address discrepancies between fundamental limits and existing state-of-the-art experimental results. We also develop the scaling length theory for 2D transistors using TCAD simulations and ~10 nm scale experimental devices, highlighting deviations from scaling theory of SOI transistors. We also introduce the physics-based Stanford 2D Semiconductor (S2DS) compact model, publicly available on the nanoHUB.org, and use it to study variability challenges in 2D circuits. This work provides key sets of guidelines towards the development of 2D transistor technology, as well as understanding its fundamental limitations.

Видео Two-Dimensional Materials and Devices | PhD Oral Defense, Stanford University, June 2018. канала Saurabh Suryavanshi