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Circular dichroism spectroscopy is known to provide important insights into the interplay of different degrees of freedom in quantum materials, and yet spectroscopic study of the optoelectronic responses of quantum materials to structured…
Two-dimensional (2D) materials are composed of atomically thin crystals with an enormous surface-to-volume ratio, and their physical properties can be easily subjected to the change of the chemical environment. Encapsulation with other…
Two-dimensional (2D) materials have attracted a great deal of interest in recent years. This family of materials allows for the realization of versatile electronic devices and holds promise for next-generation (opto)electronics. Their…
Optoelectronic devices based on graphene and other two-dimensional (2D) materials, such as transition metal dichalcogenides (TMDs) are the focus of wide research interest. The characterization these emerging atomically thin materials and…
The electrical response of a material when illuminated with light is a key to many optoelectronic device applications. This so-called photoresponse typically has a non-uniform spatial distribution through the active device area, and the…
Ultrathin sheets of MoS2 are a newly discovered 2D semiconductor that holds great promise for nanoelectronics. Understanding the pattern of current flow will be crucial for developing devices. In this talk, we present images of current flow…
The generation of a current by light is a key process in optoelectronic and photovoltaic devices. In band semiconductors, depletion fields associated with interfaces separate long-lived photo-induced carriers. However, in systems with…
Scalable fabrication of high quality photodetectors derived from synthetically grown monolayer transition metal dichalcogenides is highly desired and important for wide range of nanophotonics applications. We present here scalable…
The detection of photocurrents is central to understanding and harnessing the interaction of light with matter. Although widely used, transport-based detection averages over spatial distributions and can suffer from low photocarrier…
Optical spectroscopy techniques such as differential reflectance and transmittance have proven to be very powerful techniques to study 2D materials. However, a thorough description of the experimental setups needed to carry out these…
We present a method to carry out electrical and opto-electronic measurements on 2D materials using carbon fiber microprobes to directly make electrical contacts to the 2D materials without damaging them. The working principle of this…
Monolayer MoS$_2$ is a direct band gap semiconductor with potential applications in optoelectronics and photonics. MoS$_2$ also has a large optical nonlinearity. However, the atomic thickness of the monolayer limits the strength of the…
Opto-electronic devices utilizing graphene have already demonstrated unique capabilities, which are much more difficult to realize with conventional technologies. However, the requirements in terms of material quality and uniformity are…
Light induced current in two-dimensional (2D) layered materials emerges from mechanisms such as photothermoelectric effect, photovoltaic effect or nonlocal hot carrier transport. Semiconducting layered transition metal dichalcogenides have…
A new phototransistor based on the mechanically-exfoliated single-layer MoS2 nanosheet is fabricated and its light-induced electric properties are investigated in details. Photocurrent generated from the phototransistor is solely determined…
The thickness-dependent band structure of MoS2 implies that discontinuities in energy bands exist at the interface of monolayer (1L) and multilayer (ML) thin films. The characteristics of such heterojunctions are analyzed here using current…
The exploration of electronic and optoelectronic properties of two-dimensional (2D) materials has become one of the most attractive line of research since the isolation of graphene. Such 'all-surface materials' present a strong sensitivity…
Ultra-thin two-dimensional (2D) materials have gained significant attention for making next-generation optoelectronic devices. Here, we report a large-area heterojunction photodetector fabricated using a liquid metal-printed 2D…
The mechanisms underlying the intrinsic photoresponse of few-layer (FL) molybdenum disulphide (MoS2) field-effect transistors are investigated via scanning photocurrent microscopy. We attribute the locally enhanced photocurrent to…
Arrays of photodetector-based pixel sensors are ubiquitous in modern devices, such as smart phone cameras, automobiles, drones, laptops etc. Two dimensional (2D) material-based photodetector arrays are a relevant candidate, especially for…