Improving mobility of silicon metal-oxide-semiconductor devices for quantum dots by high vacuum activation annealing

TL;DR

This paper demonstrates that high vacuum activation annealing significantly enhances the mobility of silicon MOS devices, leading to improved quantum dot fabrication quality, which is crucial for silicon-based quantum computing advancements.

Contribution

The study reveals the benefits of high vacuum environment during activation annealing, achieving doubled mobility and high-quality quantum dot fabrication on commercial wafers.

Findings

Peak mobility improved by a factor of two to 1.5 m^2/(Vs).

High vacuum annealing reduces disorder effects at the Si/SiO2 interface.

Quantum dots show no visible disturbance from disorder.

Abstract

To improve mobility of fabricated silicon metal-oxide-semiconductor (MOS) quantum devices, forming gas annealing is a common method used to mitigate the effects of disorder at the Si/SiO2 interface. However, the importance of activation annealing is usually ignored. Here, we show that a high vacuum environment for implantation activation is beneficial for improving mobility compared to nitrogen atmosphere. Low-temperature transport measurements of Hall bars show that peak mobility can be improved by a factor of two, reaching 1.5 m^2/(Vs) using high vacuum annealing during implantation activation. Moreover, the charge stability diagram of a single quantum dot is mapped, with no visible disturbance caused by disorder, suggesting possibility of fabricating high-quality quantum dots on commercial wafers. Our results may provide valuable insights into device optimization in silicon-based quantum computing.