Date of Award

2018

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Electrical Engineering (PhD)

Administrative Home Department

Department of Electrical and Computer Engineering

Advisor 1

Paul Bergstrom

Advisor 2

John Jaszczak

Committee Member 1

Yoke Khin Yap

Committee Member 2

Elena Semouchkina

Committee Member 3

Warren Perger

Abstract

Electronic devices, especially MOSFETs, have been dimensionally scaled down to enhance operation of integrated circuits, addressing challenges such as current leakage, fluctuation of intrinsic semiconductor properties, and power dissipation. Reaching dimensions below 20 nm, there are fundamental limitations that are difficult to overcome, driving alternative device paradigms to be sought utilizing the quantum mechanical behavior of electrons. Single electron transistor (SET) devices are examples of a new generation of low-power transistors designed to transport information via single electron tunneling through one or more islands separated by tunnel junctions. Experimentally explored SET devices have shown that there are advantages to using semiconductors for the islands as compared to using metallic islands. Although semiconducting SET devices have been experimentally explored, the simulation of the transport characteristics of such devices remains an area requiring further development for gaining deeper insights into the device behavior. Progress has been limited due to the complexity of the underlying physics of electron tunneling to and from a semiconducting nanometer-scale island. Ab initio calculations are capable of accurate modeling of the physics, but are computationally prohibitive given the nanometer scales represented in the system.

This work is dedicated to understanding the behavior of electron transport involving semiconducting islands and has led to development of a kinetic Monte Carlo (KMC)-based algorithm to simulate the current-voltage characteristics of single electron transistor (SET) devices comprised of one or two semiconducting nanometer-scale islands and three electrodes (source, drain and gate) with regard to the terminal potentials, temperature. The impact of the band gap, the more complex density of states, charging energy, and island-size-dependent discreteness of energy levels in a semiconducting island on the tunneling rate are also examined.

Semiconducting islands provide parameters that can be utilized to control the SET characteristics. The alignment of the semiconducting island’s band gap with the Fermi energy of the electrodes can be tuned to control the degree of temperature’s impact on the currant-voltage characteristics of the device. It is confirmed in this work that our model is generalizable to predict electron tunneling in materials with different band structure.

Download

Share

COinS