Colloidal Indium Arsenide quantum dots as short-wave infrared single photon emitters

Introduction

MOONSHOT aims at developing a novel single-photon emitting material that operates in the telecommunication wavelength range (1300-1600 nm, O- and C-bands) and is compliant with the “Restriction of Hazardous Substances in Electrical and Electronic Equipment” (RoHS).

Motivation

The main motivation for such an objective is that single-photon sources based on epitaxial quantum dots (QDs) are now a mature technology available on the market that is outperforming laser cooled atoms or spontaneous parametric down conversion via nonlinear crystals.

Challenges with Epitaxial QDs

Yet, three major issues afflict epitaxial QDs:

1. The epitaxial approach presents drawbacks in terms of limited throughput and CMOS incompatibility.
2. Often, the emission wavelength of epitaxial QDs for single-photon generation is limited to less than 1000 nm.
3. Single-photon sources based on this class of QDs require low-temperature operation (T ≈ 4K).

Advantages of Colloidal QDs

Colloidal QDs present similar light-emission properties to their epitaxial counterparts and they can tackle most of the drawbacks of the latter. For example:

• Solution processing enables controlled placement of QDs on-chip.
• Very high throughput preparation via wet-chemistry approaches.
• Potential for operation beyond cryogenic temperatures.

Current Limitations

Nonetheless, state-of-the-art colloidal QDs with shortwave infrared emission (SWIR, 750-1600 nm) contain either lead or mercury, which are severely restricted by the RoHS. Indium arsenide (InAs) QDs are among the few SWIR-emitting RoHS-compliant materials; yet only a limited number of synthetic approaches lead to emissive QDs.

Project Focus

MOONSHOT will focus on developing highly emissive and blinking-free InAs colloidal QDs based on a synthetic route employing commercially available precursors.

Strategy

MOONSHOT adopts a high-risk strategy to realize a new technology in the field of quantum light sources with an immediate outcome in the form of optimized single-photon SWIR emitting QDs.