Electron and hole spin relaxation in InP-based self-assembled quantum dots emitting at telecom wavelengths

TL;DR

This study examines electron and hole spin relaxation in InP-based quantum dots emitting at telecom wavelengths, revealing temperature-dependent relaxation times influenced by phonon scattering and nuclear fields.

Contribution

It provides new insights into the temperature dependence of spin relaxation times in InP-based quantum dots emitting at telecom wavelengths.

Findings

Electron spin relaxation time exceeds 0.5 microseconds at low temperatures.

Electron spin relaxation decreases to 0.1 ns at 260 K due to phonon scattering.

Hole spin relaxation is more effectively activated by temperature increase.

Abstract

We investigate the electron and hole spin relaxation in an ensemble of self-assembled InAs/In$_{0.53}$Al$_{0.24}$Ga$_{0.23}$As/InP quantum dots with emission wavelengths around $1.5$~$\mu$m by pump-probe Faraday rotation spectroscopy. Electron spin dephasing due to the randomly oriented nuclear Overhauser fields is observed. At low temperatures we find a sub-microsecond longitudinal electron spin relaxation time $T_1$ which unexpectedly strongly depends on temperature. At high temperatures the electron spin relaxation time is limited by optical phonon scattering through spin-orbit interaction decreasing down to $0.1$~ns at 260~K. We show that the hole spin relaxation is activated much more effectively by a temperature increase compared to the electrons.