A5052772817- 2D Materials and Applications
- Graphene research and applications
- Topological Materials and Phenomena
- Perovskite Materials and Applications
- Semiconductor materials and devices
- Advancements in Semiconductor Devices and Circuit Design
- Quantum and electron transport phenomena
- Integrated Circuits and Semiconductor Failure Analysis
- Photonic and Optical Devices
- Quantum Dots Synthesis And Properties
- MXene and MAX Phase Materials
- Plasmonic and Surface Plasmon Research
- Advanced Fiber Laser Technologies
- Conducting polymers and applications
- Ferroelectric and Negative Capacitance Devices
- VLSI and Analog Circuit Testing
- Low-power high-performance VLSI design
- Laser-Matter Interactions and Applications
- Organic Electronics and Photovoltaics
- Chalcogenide Semiconductor Thin Films
- Spectroscopy and Quantum Chemical Studies
- Terahertz technology and applications
- Molecular Junctions and Nanostructures
- Photonic Crystals and Applications
- Electrochemical sensors and biosensors
University of California, Riverside
2024-2025
Institute for Basic Science
2017-2024
Pohang University of Science and Technology
2019-2021
Yonsei University
2013-2018
Georgia Institute of Technology
2014-2017
Abstract The photocurrent conversions of transition metal dichalcogenide nanosheets are unprecedentedly impressive, making them great candidates for visible range photodetectors. Here we demonstrate a method fabricating micron-thick, flexible films consisting variety highly separated excellent band-selective photodetection. Our is based on the non-destructive modification sheets with amine-terminated polymers. universal interaction between amine and resulted in scalable, stable high...
Two-dimensional stacks of dissimilar hexagonal monolayers exhibit unusual electronic, photonic and photovoltaic responses that arise from substantial interlayer excitations. Interband excitation phenomena in individual monolayer occur states at band edges (valleys) the momentum space; therefore, low-energy can be directed by two-dimensional rotational degree each crystal. However, this rotation-dependent is largely unknown, due to lack control over relative rotations, thereby leading...
Abstract Two-dimensional layered transition-metal dichalcogenides have attracted considerable interest for their unique layer-number-dependent properties. In particular, vertical integration of these two-dimensional crystals to form van der Waals heterostructures can open up a new dimension the design functional electronic and optoelectronic devices. Here we report photocurrent generation in graphene/MoS 2 /graphene by creating device with two distinct regions containing one-layer...
While tremendous efforts have been made for developing thin perovskite films suitable a variety of potential photoelectric applications such as solar cells, field-effect transistors, and photodetectors, only few works focus on the micropatterning film which is one most critical issues large area uniform microarrays perovskite-based devices. Here we demonstrate simple but robust method with controlled crystalline structure guarantees to preserve its intrinsic properties. A micropatterns are...
Two-dimensional surface-scattering dynamics are central in the physics of topological insulators. Numerous electrical and optical measurements have evidenced that origins novel optoelectronic response can be traced back to Dirac surface-electron dynamics. Intrinsic surface dynamics, however, remain elusive because these experiments cannot access frequencies rate. Time-resolved terahertz spectroscopy is only apparatus for directly probing collective low-energy electronic transitions. Here, by...
Abstract The optical Stark effect is a coherent light–matter interaction describing the modification of quantum states by non-resonant light illumination in atoms, solids and nanostructures. Researchers have strived to utilize this control exciton states, aiming realize ultra-high-speed switches modulators. However, most studies focused on only lowest state due lack energy selectivity, resulting low degree-of-freedom devices. Here, applying linearly polarized laser pulse few-layer ReS 2 ,...
Broadband detection of mid-infrared (IR) photons extends to advanced optoelectronic applications such as imaging, sensing, and telecommunications. While graphene offers an attractive platform for broadband visible/IR photodetection, previous efforts improve its responsivity, example, by integrating light-absorbing colloids or waveguide antenna fabrication, were achieved at the cost reduced photon bandwidth. In this work, we demonstrate room-temperature operation a novel mid-IR photodetector...
Modulating light via coherent charge oscillations in solids is the subject of intense research topics opto-plasmonics. Although a variety methods are proposed to increase such modulation efficiency, one central challenge achieve high depth (defined by ratio extinction with/without light) under small photon-flux injection, which becomes fundamental trade-off issue both metals and semiconductors. Here, fabricating simple micro-ribbon arrays topological insulator Bi2Se3, we report an...
Abstract The 1 s exciton—the ground state of a bound electron-hole pair—is central to understanding the photoresponse monolayer transition metal dichalcogenides. Above exciton, recent visible and near-infrared investigations have revealed that excited excitons are much richer, exhibiting series Rydberg-like states. A natural question is then how internal excitonic transitions interrelated on photoexcitation. Accessing these intraexcitonic transitions, however, demands fundamentally different...
Abstract Hexagonal boron nitride (hBN) is a van der Waals semiconductor with wide bandgap of ~ 5.96 eV. Despite the indirect characteristics hBN, charge carriers excited by high energy electrons or photons efficiently emit luminescence at deep-ultraviolet (DUV) frequencies via strong electron-phonon interaction, suggesting potential DUV light emitting device applications. However, electroluminescence from hBN has not been demonstrated so far. In this study, we report and photocurrent...
Higher-order topological insulators are recently discovered quantum materials exhibiting distinct phases with the generalized bulk-boundary correspondence. Td-WTe2 is a promising candidate to reveal hinge excitation in an atomically thin regime. However, initial theories and experiments focusing on localized one-dimensional conductance only, no experimental reports exist how spin orientations distributed over helical hinges-this critical, yet one missing puzzle. Here, we employ magneto-optic...
Quantum beats, periodic oscillations arising from coherent superposition states, have enabled exploration of novel phenomena. Originating strong Coulomb interactions and reduced dielectric screening, two-dimensional transition metal dichalcogenides exhibit strongly bound excitons either in a single structure or hetero-counterpart; however, quantum coherence between is barely known to date. Here we observe exciton beats atomically thin ReS
Under strong laser fields, electrons in solids radiate high-harmonic fields by travelling through quantum pathways Bloch bands the sub-laser-cycle timescales. Understanding these momentum space radiation can enable an all-optical ultrafast probe to observe coherent lightwave-driven processes and measure electronic structures as recently demonstrated for semiconductors. However, such demonstration has been largely limited semimetals because absence of bandgap hinders experimental...
Asymmetric Fano resonance arises from quantum interference between discrete and continuum states. The characteristic asymmetry has attracted strong interests in understanding light-induced optoelectronic responses corresponding applications. In conventional solids, however, the tunability of is generally limited by a material's intrinsic property. Topological insulators are unique states matter embodying both conducting Dirac surface underlying bulk. If it possible to manipulate two...
Strong interactions between excitons are a characteristic feature of two-dimensional (2D) semiconductors, determining important excitonic properties, such as exciton lifetime, coherence, and photon-emission efficiency. Rhenium disulfide ($\mathrm{Re}{\mathrm{S}}_{2}$), member the 2D transition-metal dichalcogenide (TMD) family, has recently attracted great attention due to its unique that exhibit excellent polarization selectivity coherence features. However, an in-depth understanding...
Abstract Moiré superlattices of transition metal dichalcogenides offer a unique platform to explore correlated exciton physics with optical spectroscopy. Whereas the spatially modulated potentials evoke that resonances are distinct depending on site in moiré supercell, there have been no clear demonstration how excitons trapped different sites dynamically interact doped carriers; so far exciton-electron dynamic interactions were presumed be site-dependent. Thus, transient emergence...
Negative bias temperature instability (NBTI), positive (PBTI) and hot carrier injection (HCI) are leading reliability concerns for modern microprocessors. In this paper, a framework is proposed to analyze the impact of NBTI, PBTI HCI on state-of-art microprocessors accurately estimate microprocessor lifetimes due each wearout mechanism. Our methodology finds detailed electrical stress device within system running variety standard benchmarks. Combining profiles, thermal device-level models,...
Coherent light–matter interaction can transiently modulate the quantum states of matter under nonresonant laser excitation. This phenomenon, called optical Stark effect, is one promising candidates for realizing ultrafast switches. However, modulations induced by coherent interactions usually involve unwanted incoherent responses, significantly reducing overall operation speed. Here, using pump–probe spectroscopy, we suppress response and coherent-to-incoherent ratio in two-dimensional...