Alexandria Digital Research Library

Atomic-scale investigations of current and future devices : from nitride-based transistors to quantum computing

Degree Grantor:
University of California, Santa Barbara. Materials
Degree Supervisor:
Chris G. Van de Walle
Place of Publication:
[Santa Barbara, Calif.]
University of California, Santa Barbara
Creation Date:
Issued Date:
Engineering, Materials Science
Oxide interfaces
Quantum computing
Schrodinger-Poisson simulations
Density-functional theory
Dissertations, Academic and Online resources
Ph.D.--University of California, Santa Barbara, 2014

Our era is defined by its technology, and our future is dependent on its continued evolution. Over the past few decades, we have witnessed the expansion of advanced technology into all walks of life and all industries, driven by the exponential increase in the speed and power of semiconductor-based devices.

However, as the length scale of devices reaches the atomic scale, a deep understanding of atomistic theory and its application is increasingly crucial. In order to illustrate the power of an atomistic approach to understanding devices, we will present results and conclusions from three interlinked projects: n-type doping of III-nitride semiconductors, defects for quantum computing, and macroscopic simulations of devices.

First, we will study effective n-type doping of III-nitride semiconductors and their alloys, and analyze the barriers to effective n-type doping of III-nitrides and their alloys. In particular, we will study the formation of DX centers, and predict alloy composition onsets for various III-nitride alloys. In addition, we will perform a comprehensive study of alternative dopants, and provide potential alternative dopants to improve n-type conductivity in AlN and wide-band-gap nitride alloys.

Next, we will discuss how atomic-scale defects can act as a curse for the development of quantum computers by contributing to decoherence at an atomic scale, specifically investigating the effect of two-level state defects (TLS) systems in alumina as a source of decoherence in superconducting qubits based on Josephson junctions; and also as a blessing, by allowing the identification of wholly new qubits in different materials, specifically showing calculations on defects in SiC for quantum computing applications.

Finally, we will provide examples of recent calculations we have performed for devices using macrosopic device simulations, largely in conjunction with first-principles calculations. Specifically, we will discuss the power of using a multi-scale approach to accurately model oxide and nitride-based heterostructures, and thereby illustrate our ability to predict device performance on scales unreachable using a purely first-principles approach.

Physical Description:
1 online resource (208 pages)
UCSB electronic theses and dissertations
Catalog System Number:
Inc.icon only.dark In Copyright
Copyright Holder:
Luke Gordon
File Description
Access: Public access
Gordon_ucsb_0035D_12312.pdf pdf (Portable Document Format)