Research

Research on the optical and excitonic properties of 2D heterostructures aims to leverage their strong light-matter interactions for quantum and optoelectronic applications. These materials' unique quantum confinement effects are explored to enhance device functionalities in technologies like solar cells and quantum computing. Manipulating these properties could lead to significant developments in quantum optical devices and photonic systems.

Shreetu et al. (2023) explore the phenomenon of room-temperature valley polarization, opening up new avenues for quantum communication. L. Gu (2024) investigates the giant optical nonlinearity of Fermi polarons in thin semiconductors, which could lead to advancements in nonlinear optical devices. Meanwhile, Zhang et al. (2024) focus on the electrical control and transport properties of tightly bound interlayer excitons, demonstrating the ability to tailor electronic and optical functionalities within 2D heterostructures.

The study of energy transfer and interlayer dynamics in 2D materials addresses how excitons and charges interact across layered materials. Understanding these mechanisms is key to designing devices that use efficient energy transfer for enhanced performance, impacting applications in photovoltaics, photocatalysis, and light-emitting devices. This research not only advances material science but also boosts the energy efficiency of nanoscale devices.

In the realm of energy transfer and interlayer dynamics within 2D materials, the research led by Arka Karmakar et al. (2023) stands out. Their work on excitation-dependent high-lying excitonic exchange through interlayer energy transfer provides a deeper understanding of the energetic interactions across layered materials. This research is crucial for developing devices that leverage these interactions to enhance efficiency and performance, potentially leading to innovations in energy conversion and storage technologies.

Studies focused on the QPress facility have led to significant advancements in interface cleaning of heterostructures, particularly concerning polymer-contaminated graphene. Research spearheaded by Huang et al (2022). has demonstrated systematic approaches to mitigate interfacial contaminants by employing thermal and mechanical actuation strategies. These methods involve the precise manipulation of conditions using QPress stacker, such as temperature and pressure to mobilize and remove residues that impact the quality of heterostructures, resulting in cleaner interfaces and enhanced electronic properties. Such methodologies are critical for pushing the capabilities of 2D materials in technological applications, including quantum computing and advanced electronic devices.

A distinct category of research utilizing QPress involves the exploration and manipulation of 2D materials to create moiré heterostructures, which hold profound potential in quantum materials science. By controlling the stacking angle and alignment of different 2D layers, researchers can induce new physical properties arising from the moiré patterns. This area is particularly promising for discovering new quantum phenomena and enhancing device functionalities, leveraging the precise assembly and characterization capabilities of the QPress system.

Characterizing ultrathin 2D materials poses a significant challenge, requiring assessments of structural, chemical, optical, and electronic properties through various techniques, such as optical spectroscopy, scanning probe methods, and electron spectro-microscopy. Traditional substrates often fall short due to issues like charging from insulating oxide layers. To address this, the QPress team developed specialized substrates composed of silicon wafers with a conventional SiO2 layer topped with a thin, engineered layer of reduced titania. This design optimizes optical thickness for measurements while providing charge dissipation through the semiconducting TiOx layer, facilitating the use of techniques like LEEM, LEED, XPEEM, ARPES, and XPS. These substrates have enabled the mapping and detailed study of properties such as twisted-bilayer graphene films, revealing unique electronic structures that hold promise for novel opto-electronic devices, as demonstrated in research by Dai et al. (2021)