Spin-Lattice Relaxation in Si Quantum Dots

TL;DR

This paper investigates how phonon-induced strain affects spin-lattice relaxation in silicon quantum dots, revealing anisotropic relaxation rates and partial suppression of two-phonon processes due to valley structure effects.

Contribution

It provides a detailed analysis of spin relaxation mechanisms in Si quantum dots, highlighting the impact of valley structure on relaxation anisotropy and suppression.

Findings

Strong anisotropy in relaxation rates due to valley effects

Partial suppression of two-phonon relaxation compared to donors

Dependence of relaxation on quantum dot confinement and orientation

Abstract

We consider spin-lattice relaxation processes for electrons trapped in lateral Si quantum dots in a $[001]$ inversion layer. Such dots are characterized by strong confinement in the direction perpendicular to the surface and much weaker confinement in the lateral direction. The spin relaxation is assumed to be due to the modulation of electron $g$-factor by the phonon-induced strain, as was shown previously for the shallow donors. The results clearly indicate that the specific valley structure of the ground electron state in Si quantum dots causes strong anisotropy for both the one-phonon and two-phonon spin relaxation rates. In addition, it gives rise to a partial suppression of the two-phonon relaxation in comparison to the spin relaxation of donor electrons.