Quantum Efficiency and Oscillator Strength of InGaAs Quantum Dots for Single-Photon Sources emitting in the Telecommunication O-Band

TL;DR

This study experimentally measures the oscillator strength and internal quantum efficiency of InGaAs quantum dots with strain-reducing layers, demonstrating their suitability as single-photon sources in the telecom O-Band.

Contribution

It provides the first detailed experimental evaluation of OS and IQE for InGaAs QDs emitting in the telecom O-Band using a novel decay rate analysis method.

Findings

Oscillator strength of 24.6 ± 3.2 measured.

High internal quantum efficiency of about 85%.

Quantum dots suitable for telecom single-photon sources.

Abstract

We demonstrate experimental results based on time-resolved photoluminescence spectroscopy to determine the oscillator strength (OS) and the internal quantum efficiency (IQE) of InGaAs quantum dots (QDs). Using a strain-reducing layer (SRL) these QDs can be employed for the manufacturing of single-photon sources (SPS) emitting in the telecom O-Band. The OS and IQE are evaluated by determining the radiative and non-radiative decay rate under variation of the optical density of states at the position of the QD as proposed and applied in J. Johansen et al. Phys. Rev. B 77, 073303 (2008) for InGaAs QDs emitting at wavelengths below 1 $\mu$m. For this purpose, we perform measurements on a QD sample for different thicknesses of the capping layer realized by a controlled wet-chemical etching process. From numeric modelling the radiative and nonradiative decay rates dependence on the capping layer thickness, we determine an OS of 24.6 $\pm$ 3.2 and a high IQE of about (85 $\pm$ 10)% for the long-wavelength InGaAs QDs.