Spin relaxation and donor-acceptor recombination of Se$^+$ in 28-silicon

TL;DR

This paper investigates the electron spin relaxation and coherence times of Se$^{+}$ donors in isotopically purified 28-silicon, revealing significantly longer times than group V donors, and explores donor-acceptor recombination control via optical excitation.

Contribution

It provides the first detailed measurements of spin relaxation and coherence times of Se$^{+}$ in silicon and demonstrates charge state control through optical means.

Findings

Se$^{+}$ has longer $T_1$ and $T_2$ times than group V donors above 15 K.

Donor-acceptor recombination dynamics can be controlled optically.

Charge state of selenium donors can be manipulated with light.

Abstract

Selenium impurities in silicon are deep double donors and their optical and electronic properties have been recently investigated due to their application for infrared detection. However, a singly-ionised selenium donor (Se$^{+}$) possesses an electron spin which makes it a potential candidate as a silicon-based spin qubit, with significant potential advantages compared to the more commonly studied group V donors. Here we study the electron spin relaxation ($T_1$) and coherence ($T_2$) times of Se$^{+}$ in isotopically purified 28-silicon, and find them to be up to two orders of magnitude longer than shallow group V donors at temperatures above $\sim 15$ K. We further study the dynamics of donor-acceptor recombination between selenium and boron, demonstrating that it is possible to control the donor charge state through optical excitation of neutral Se$^0$.