Princeton University

School of Engineering & Applied Science

Development and Characterization of Low-Disorder Metal-Oxide-Silicon Quantum Dot Devices

Speaker: 
Jin-Sung Kim
Advisor: 
Prof. Lyon
Location: 
Engineering Quadrangle J-401
Date/Time: 
Wednesday, October 24, 2018 - 3:15pm to 4:45pm

Abstract

Quantum computers promise an exponential speed-up in certain classes of computational problems which, when realized, will have profound consequences in the fields of chemistry, physics, artificial intelligence, and more. An open question today is what platform to build a scalable universal quantum processor on, and many systems are currently active areas of research (superconducting circuits, trapped ions, semiconductor quantum dots, electrons on helium, etc). One such promising system consists of electron and donor spins as quantum bits (qubits) confined in Metal-Oxide-Silicon (MOS) quantum dot devices. Spins in silicon demonstrate long coherence times, the characteristic timescale in which quantum information can be preserved. In addition, silicon benefits from the mature fabrication infrastructure of the CMOS industry, which offers a tantalizing roadmap towards very large quantum systems on a single silicon chip. Despite the incredible advances made in materials and fabrication techniques by the CMOS industry, and continued by the silicon quantum electronics community, many challenges remain in building a silicon quantum processor. One of the biggest challenges in this field is the presence of disorder at the Si/SiO2 interface which can interfere with quantum operations at the single-electron level

In this dissertation, we discuss the development and characterization of a low-disorder MOS double quantum dot device. To realize these low-disorder devices, we first develop a process yielding the highest reported mobility for a thin-oxide MOSFET and with very low shallow defect densities and utilize these high-quality samples as an experimental platform. As quantum devices must operate at cryogenic temperatures, the defects relevant to these quantum devices are distinct from the ones studied in classical MOS devices and require novel methods of characterization. Using electron spin resonance, we show that shallow electron traps (the defect most detrimental to quantum devices in MOS) can be passivated using standard annealing treatments. Finally, we discuss the performance of our double quantum dot device, demonstrating low levels of disorder and other device characteristics demonstrating a promising platform for scaling to larger quantum systems in MOS.