Germanium-based quantum emitters for time-reordering entanglement scheme with degenerate exciton and biexciton states

TL;DR

This paper investigates germanium-based quantum emitters in AlGaAs epilayers, demonstrating their high-temperature emission, multiexcitonic features, and energy level renormalization, highlighting their potential for entangled photon generation.

Contribution

It provides the first detailed analysis of germanium extrinsic centers showing multiexcitonic emission and energy level tuning for quantum information applications.

Findings

High-temperature emission at 70 K

Observation of multiexcitonic features (X, XX, X+, X-)

Systematic energy level renormalization with quantum confinement

Abstract

We address the photoluminescence emission of individual germanium extrinsic centers in Al_0.3Ga0.7As epilayers grown on germanium substrates. Through a thorough analysis of micro-photoluminescence experiments we demonstrate the capability of high temperature emission (70 K) and multiexcitonic features (neutral exciton X, biexciton XX, positive X+ and negative X- charged exciton) of these quantum emitters. Finally, we investigate the renormalization of each energy level showing a large and systematic change of the binding energy of XX and X+ from positive to negative values (from ~+5 meV up to ~-7 meV covering about ~ 70 meV of the emission energy) with increasing quantum confinement. These light emitters exhibiting energy-degenerate X and XX energy levels at ~1.855 eV (680 nm) are a promising resource for the generation of entangled photons in the time-reordering scheme on a silicon platform.