Atomically-Thin Opto-Electro-Mechanical deviceS – ATOEMS

Major recent progress in photonics, optoelectronics and optomechanics has been enabled by improvements in the quality of low-dimensional materials. Two-dimensional materials (2DM, semiconducting transition metal dichalcogenides (TMD) and graphene) are examples of choice. They display remarkable electronic properties and strong light-matter interactions. 2DMs are highly sensitive to their local environment and are building blocks of choice for van der Waals heterostructures (vdWH, i.e., stacks of 2DM), in which the properties of 2DM can be engineered and enhanced. At the same time, 2DM are lightweight, ultrasensitive nanomechanical systems that are controllable by externally applied strain.
Although a variety of opto-electronic devices and nano-mechanical resonators made from 2DM and vdWH have been demonstrated, the subtle connections between the microscopic properties (e.g., excitons, phonons, interlayer coupling) of 2DM and the macroscopic optoelectronic and mechanical figures of merit remain an uncharted territory.

The exceptional emission characteristics, tunability and sensing capabilities of 2DM pave the way for the novel class of atomically-thin opto-electro-mechanical devices (ATOEMS). ATOEMS will be highly controllable light-emitting devices with improved performances achieved by exploiting physical features and proximity effects that are inherent to 2DM. Conversely, we envision ATOEMS as ultra-sensitive probes of local perturbations. Our consortium will implement a synergistic, approach towards the following objectives:

O1) Synthesizing and characterizing TMD bulk crystals and monolayers with unprecedentedly low defect and dopant densities.
O2) With these crystals, fabricating ultraclean, suspended vdWH with control over the rotational mismatch and moiré patterns. Characterizing their optical response, including in the near-IR range.
O3) Investigating interlayer charge and energy transfer and moiré-trapped excitons in vdWH with radiatively-limited emission features.
O4) Designing a unique opto-electro-mechanical platform that combines state of the art nano-mechanical actuation and motion readout with time-resolved optical spectroscopy.
O5) Achieving dynamical strain-mediated control of the light emission characteristics in 2DM. Conversely, using phonons and excitons as sensitive probes of strain.
O6) Achieving electro-mechanical tuning of i) interlayer coupling at the Ångström to sub-Ångström scales and ii) exciton localization in the moiré superpotentials present in TMD heterobilayers.
O7) Demonstrating photo- and electroluminescent quantum devices that harnesses the properties above and will operate in the single photon regime, in the visible and near-IR ranges.

ATOEMS tackles the technologically-relevant challenge to develop a new class of light-emitting nanoscale devices with a fundamental approach that differs from those developed in semiconductor physics and engineering.
We will push van der Waals engineering to its limits but also introduce a new experimental methodology allowing ultra-fine tuning and temporal modulation of interlayer distance and rotational mismatch at the relevant scales (sub-Ångström and sub-10-2 radian, respectively). As a result, we will control dielectric screening, exciton dynamics, and last but not least, moiré physics (exciton localization, exciton diffusion) with unprecedented accuracy.

The joint exploitation of the photophysical and mechanical properties of 2DM will allow us i/to propose new concepts contributing to the rising fields of straintronics and twistronics and ii/ to achieve device performances beyond the state of the art, such as electro-mechanical tuning of light emission characteristics, near unity emission yield, deterministic operation in the single photon regime, and importantly, compatibility with silicon photonic integrated circuits and operation at telecom wavelengths (cf. O2). These functionalities will enable a leap forward for devices based on 2DM.