MBE-grown virtual substrates for quantum dots emitting in the telecom O- and C-bands

TL;DR

This paper presents an optimized molecular beam epitaxy method to grow InAs quantum dots on virtual substrates, achieving tunable emission in the telecom O- and C-bands for quantum photonic applications.

Contribution

It introduces a novel heterostructure design using compositionally graded InGaAs buffers as virtual substrates for telecom-band quantum dots.

Findings

Achieved tunable photoluminescence from 1200 to 1600 nm.

Observed exciton-biexciton complexes in the telecom bands.

Demonstrated a flexible platform for quantum photonic device integration.

Abstract

InAs semiconductor quantum dots (QDs) emitting in the near infrared are promising platforms for on-demand single-photon sources and spin-photon interfaces. However, the realization of quantum-photonic nanodevices emitting in the second and third telecom windows with similar performance remains an open challenge. Here, we report an optimized heterostructure design for QDs emitting in the O- and C-bands grown by means of molecular beam epitaxy. The InAs QDs are grown on compositionally graded InGaAs buffers, which act as virtual substrates, and are embedded in mostly relaxed active regions. Reciprocal space maps of the indium profiles and optical absorption spectra are used to optimize In0.22Ga0.78As and In0.30Ga0.70As active regions, accounting for the chosen indium grading profile. This approach results in a tunable QD photoluminescence (PL) emission from 1200 up to 1600 nm. Power and polarization dependent micro-PL measurements performed at 4 K reveal exciton-biexciton complexes from quantum dots emitting in the telecom O- and C-bands. The presented study establishes a flexible platform that can be an essential component for advanced photonic devices based on InAs/GaAs that serve as building blocks for future quantum networks.