A5070787716- 2D Materials and Applications
- Graphene research and applications
- Perovskite Materials and Applications
- Semiconductor Quantum Structures and Devices
- Quantum Dots Synthesis And Properties
- Diamond and Carbon-based Materials Research
- Quantum and electron transport phenomena
- Chalcogenide Semiconductor Thin Films
- Molecular Junctions and Nanostructures
- Boron and Carbon Nanomaterials Research
- MXene and MAX Phase Materials
- Topological Materials and Phenomena
- Semiconductor materials and devices
- Semiconductor Lasers and Optical Devices
- Advanced Semiconductor Detectors and Materials
- Advancements in Battery Materials
- Solid-state spectroscopy and crystallography
- Magnetic properties of thin films
- Advanced Fiber Laser Technologies
- Electronic and Structural Properties of Oxides
- Phase-change materials and chalcogenides
- Multiferroics and related materials
- Advanced Photocatalysis Techniques
- Spectroscopy and Quantum Chemical Studies
- Quantum Information and Cryptography
National University of Singapore
2020-2025
Institute of Molecular Functional Materials
2025
Université Bourgogne Franche-Comté
2025
Polish Academy of Sciences
2010-2022
Instytut Biologii Doświadczalnej im. Marcelego Nenckiego
2022
Mossakowski Medical Research Institute, Polish Academy of Sciences
2022
University of Manchester
2018-2020
Laboratoire National des Champs Magnétiques Intenses
2015-2019
Centre National de la Recherche Scientifique
2015-2019
Université Grenoble Alpes
2015-2019
We present optical spectroscopy (photoluminescence and reflectance) studies of thin layers the transition metal dichalcogenide WSe2, with thickness ranging from mono- to tetra-layer in bulk limit. The investigated spectra show evolution excitonic resonances as a function layer thickness, due changes band structure and, importantly, modifications strength Coulomb interactions well. observed temperature-activated energy shift broadening fundamental direct exciton are well accounted for by...
Abstract Recent results on the optical properties of monolayer and few layers semiconducting transition metal dichalcogenides are reviewed. Experimental observations presented discussed in frame existing models, highlighting limits our understanding this emerging field research. We first introduce representative band structure these systems their interband transitions. The effect an external magnetic is then considered to discuss Zeeman spectroscopy pumping experiments, both revealing...
By implementing four-wave mixing (FWM) microspectroscopy, we measure coherence and population dynamics of the exciton transitions in monolayers MoSe2. We reveal their dephasing times T2 radiative lifetime T1 a subpicosecond (ps) range, approaching = 2T1 thus indicating radiatively limited at temperature 6 K. elucidate mechanisms by varying probing various locations on flake exhibiting different local disorder. At nanosecond observe residual FWM produced incoherent excitons, which initially...
Solotronics, optoelectronics based on solitary dopants, is an emerging field of research and technology reaching the ultimate limit miniaturization. It aims at exploiting quantum properties individual ions or defects embedded in a semiconductor matrix. As already shown, optical control spin magnetic ion feasible employing photo-generated carriers confined dot. A non-radiative recombination, regarded as severe problem, limited development dots with ions. Our photoluminescence studies on, so...
We present the micro-photoluminescence ($\mu$PL) and micro-reflectance contrast spectroscopy studies on thin films of MoSe2 with layer thicknesses ranging from a monolayer (1L) up to 5L. The thickness dependent evolution ground excited state excitonic transitions taking place at various points Brillouin zone is determined. Temperature activated energy shifts linewidth broadenings resonances in 1L, 2L 3L flakes are accounted for by using standard formalisms previously developed...
We present a comprehensive optical study of the excitonic Zeeman effects in transition metal dichalcogenide monolayers, which are discussed comparatively for selected materials: MoSe2, WSe2 and WS2. introduce simple semi-phenomenological description magnetic field evolution individual electronic states fundamental sub-bands by considering three additive components: valley, spin orbital terms. corroborate validity proposed inspecting Zeeman-like splitting neutral charged resonances...
Atomically thin films of III–VI post-transition metal chalcogenides (InSe and GaSe) form an interesting class two-dimensional semiconductors that feature a strong variation their band gap as function the number layers in crystal and, specifically for InSe, expected crossover from direct bulk to weakly indirect monolayers bilayers. Here, we apply angle-resolved photoemission spectroscopy with submicrometer spatial resolution (μARPES) visualize layer-dependent valence structure mechanically...
Ferromagnetism in van der Waals systems, preserved down to a monolayer limit, attracted attention class of materials with general composition CrX3 (X=I, Br, and Cl), which are treated now as canonical 2D ferromagnets. Their diverse magnetic properties, such different easy axes or varying controllable character in-plane interlayer ferromagnetic coupling, make them promising candidates for spintronic, photonic, optoelectronic, other applications. Still, significantly magneto-optical properties...
Abstract Defect centers in wide-band-gap crystals have garnered interest for their potential applications among optoelectronic and sensor technologies. However, defects embedded highly insulating crystals, like diamond, silicon carbide, or aluminum oxide, been notoriously difficult to excite electrically due large internal resistance. To address this challenge, we realized a new paradigm of exciting vertical tunneling junctions based on carbon hexagonal boron nitride (hBN). The rational...
Abstract Generation and control of topological spin textures constitutes one the most exciting challenges modern spintronics given their potential applications in information storage technologies. Of particular interest are magnetic insulators, which due to low damping, absence Joule heating reduced dissipation can provide energy‐efficient spin‐textures platform. Here, it is demonstrated that interplay between sample thickness, external fields, optical excitations generate a prolific...
A recently discovered class of two-dimensional semiconductors exhibits a novel degree freedom known as valley pseudospin. New results show that weak magnetic field can significantly extend the depolarization time this
The possibility to tailor photoluminescence (PL) of monolayer transition metal dichalcogenides (TMDCs) using external factors such as strain, doping and environment is significant interest for optoelectronic applications. Strain in particular can be exploited a means continuously vary the bandgap. Micrometer-scale strain gradients were proposed creating 'artificial atoms' that utilize so-called exciton funneling effect work, example, condensers. Here we describe room-temperature PL emitters...
Significance Well‐defined defect centers play a crucial role in condensed-matter physics. That is particularly evident the case of semiconductors and wide‐gap insulators, where midgap levels provide number versatile functionalities: from lasing to pressure sensing. Individual defects may become single-photon sources—crucial for applications quantum technology. Recently, such have been observed hexagonal boron nitride (hBN). Here, method fabricate stable reproducible hBN introduced. Large...
The creation of defect with predetermined optical, chemical, and other characteristics is a powerful tool to enhance the functionalities materials. Herewith, we utilize density functional theory understand microscopic mechanisms formation defects in hexagonal boron nitride based on vacancies substitutional atoms. Through in-depth analysis defect-induced band structure energy varying growth conditions, uncovered dominant role interdefect electron pairing stabilization complexes....
Defect centers in insulators play a critical role creating important functionalities materials: prototype qubits, single-photon sources, magnetic field probes, and pressure sensors. These are highly dependent on their midgap electronic structure orbital/spin wave function contributions. However, most cases, these fundamental properties remain unknown or speculative due to the defects being deeply embedded beneath surface of resistive host crystals, thus impeding access through probes. Here,...
We experimentally demonstrate the creation of defects in monolayer WSe2 via nanopillar imprinting and helium ion irradiation. Based on first method, we realize atomically thin vertical tunneling light-emitting diodes based monolayers hosting quantum emitters at deterministically specified locations. characterize these by investigating evolution their emission spectra external electric magnetic fields, as well inducing electroluminescence low temperatures. identify qualitatively different...
Control over the electronic spectrum at low energy is heart of functioning modern advanced electronics: high electron mobility transistors, semiconductor and Capasso terahertz lasers, many others. Most those devices rely on meticulous engineering size quantization electrons in quantum wells. This avenue, however, hasn't been explored case 2D materials. Here we transfer this concept onto van der Waals heterostructures which utilize few-layers films InSe as The precise control subbands their...
Reflectance and magneto-reflectance experiments together with theoretical modelling based on the k ⋅ p approach have been employed to study evolution of direct bandgap excitons in MoS2 layers a thickness ranging from mono- trilayer. We observe extra excitonic resonances multilayers which emerge as result hybridization Bloch states each sub-layer due interlayer coupling. The properties such bi- trilayers are classified by symmetry corresponding crystals. inter- intralayer character reported...