Spatially Resolved Photogenerated Exciton and Charge Transport in Emerging Semiconductors

2020 ◽  
Vol 71 (1) ◽  
pp. 1-30 ◽  
Author(s):  
Naomi S. Ginsberg ◽  
William A. Tisdale
Keyword(s):  
Organic Semiconductors ◽  
Energy Transport ◽  
Transition Metal Dichalcogenides ◽  
Electronic Energy ◽  
Time Resolved ◽  
Spatially Resolved ◽  
New Family ◽  
Dependent Rate ◽  
Metal Dichalcogenides ◽  
Colloidal Quantum Dot

We review recent advances in the characterization of electronic forms of energy transport in emerging semiconductors. The approaches described all temporally and spatially resolve the evolution of initially localized populations of photogenerated excitons or charge carriers. We first provide a comprehensive background for describing the physical origin and nature of electronic energy transport both microscopically and from the perspective of the observer. We introduce the new family of far-field, time-resolved optical microscopies developed to directly resolve not only the extent of this transport but also its potentially temporally and spatially dependent rate. We review a representation of examples from the recent literature, including investigation of energy flow in colloidal quantum dot solids, organic semiconductors, organic-inorganic metal halide perovskites, and 2D transition metal dichalcogenides. These examples illustrate how traditional parameters like diffusivity are applicable only within limited spatiotemporal ranges and how the techniques at the core of this review,especially when taken together, are revealing a more complete picture of the spatiotemporal evolution of energy transport in complex semiconductors, even as a function of their structural heterogeneities.

scholarly journals Energy and Charge Transport in 2D Atomic Layer Materials: Raman-Based Characterization

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1807
Author(s):  
Ridong Wang ◽  
Tianyu Wang ◽  
Hamidreza Zobeiri ◽  
Dachao Li ◽  
Xinwei Wang
Keyword(s):  
Charge Transport ◽  
Time Domain ◽  
Energy Transport ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Atomic Layer ◽  
Domain Space ◽  
Mechanical And Physical Properties ◽  
Metal Dichalcogenides

As they hold extraordinary mechanical and physical properties, two-dimensional (2D) atomic layer materials, including graphene, transition metal dichalcogenides, and MXenes, have attracted a great deal of attention. The characterization of energy and charge transport in these materials is particularly crucial for their applications. As noncontact methods, Raman-based techniques are widely used in exploring the energy and charge transport in 2D materials. In this review, we explain the principle of Raman-based thermometry in detail. We critically review different Raman-based techniques, which include steady state Raman, time-domain differential Raman, frequency-resolved Raman, and energy transport state-resolved Raman techniques constructed in the frequency domain, space domain, and time domain. Detailed outlooks are provided about Raman-based energy and charge transport in 2D materials and issues that need special attention.

scholarly journals Enhanced Photoresponsivity of 2H-MoTe2 by Inserting 1T-MoTe2 Interlayer Contact for Photodetector Applications

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 964
Author(s):  
Der-Yuh Lin ◽  
Hung-Pin Hsu ◽  
Guang-Hsin Liu ◽  
Ting-Zhong Dai ◽  
Yu-Tai Shih
Keyword(s):  
Transition Metal Dichalcogenides ◽  
Thermionic Emission ◽  
Decay Process ◽  
Frequency Dependent ◽  
Time Resolved ◽  
Barrier Heights ◽  
Potential Applicability ◽  
Metal Dichalcogenides ◽  
Electrode Contact ◽  
Layered Transition Metal

The 2H molybdenum telluride (MoTe2) photodetector structures were made with inserting 1T-MoTe2 interlayer contacts. The optical response properties such as photoconductivity (PC) spectroscopy, illumination intensity dependent photoresponsivity, frequency dependent photocurrent, and time-resolved photoresponse were carried out in this study. In PC spectra, a much higher photoresponsivity of 2H-MoTe2 were observed by inserting 1T-MoTe2 interlayer contact. The frequency dependent photocurrent and time-resolved photoresponse investigations explore the carrier kinetic decay process of MoTe2 with different electrode contact. The Schottky barrier heights (SBH) extracted by thermionic emission theory were also investigated by inserting 1T-MoTe2 interlayer contacts. The results show the potential applicability for photodetection devices based MoTe2 layered transition metal dichalcogenides semiconductors.

scholarly journals Near-field optical imaging and spectroscopy of 2D-TMDs

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Youngbum Kim ◽  
Jeongyong Kim
Keyword(s):  
Optical Imaging ◽  
Near Field ◽  
Spectral Characteristics ◽  
Transition Metal Dichalcogenides ◽  
Current Status ◽  
Carrier Distribution ◽  
Spatially Resolved ◽  
Metal Dichalcogenides ◽  
Imaging And Spectroscopy ◽  
Local Defects

Abstract Two-dimensional transition metal dichalcogenides (2D-TMDs) are atomically thin semiconductors with a direct bandgap in monolayer thickness, providing ideal platforms for the development of exciton-based optoelectronic devices. Extensive studies on the spectral characteristics of exciton emission have been performed, but spatially resolved optical studies of 2D-TMDs are also critically important because of large variations in the spatial profiles of exciton emissions due to local defects and charge distributions that are intrinsically nonuniform. Because the spatial resolution of conventional optical microscopy and spectroscopy is fundamentally limited by diffraction, near-field optical imaging using apertured or metallic probes has been used to spectrally map the nanoscale profiles of exciton emissions and to study the effects of nanosize local defects and carrier distribution. While these unique approaches have been frequently used, revealing information on the exciton dynamics of 2D-TMDs that is not normally accessible by conventional far-field spectroscopy, a dedicated review of near-field imaging and spectroscopy studies on 2D-TMDs is not available. This review is intended to provide an overview of the current status of near-field optical research on 2D-TMDs and the future direction with regard to developing nanoscale optical imaging and spectroscopy to investigate the exciton characteristics of 2D-TMDs.

scholarly journals Wafer scale synthesis of organic semiconductor nanosheets for van der Waals heterojunction devices

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Sirri Batuhan Kalkan ◽  
Emad Najafidehaghani ◽  
Ziyang Gan ◽  
Fabian Alexander Christian Apfelbeck ◽  
Uwe Hübner ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Physical Vapor Deposition ◽  
Field Effect Transistors ◽  
Van Der Waals ◽  
Transition Metal Dichalcogenides ◽  
Wafer Scale ◽  
Heterojunction Devices ◽  
Wide Range ◽  
Conformal Electronics ◽  
Metal Dichalcogenides

AbstractOrganic semiconductors (OSC) are widely used for consumer electronic products owing to their attractive properties such as flexibility and low production cost. Atomically thin transition metal dichalcogenides (TMDs) are another class of emerging materials with superior electronic and optical properties. Integrating them into van der Waals (vdW) heterostructures provides an opportunity to harness the advantages of both material systems. However, building such heterojunctions by conventional physical vapor deposition (PVD) of OSCs is challenging, since the growth is disrupted due to limited diffusion of the molecules on the TMD surface. Here we report wafer-scale (3-inch) fabrication of transferable OSC nanosheets with thickness down to 15 nm, which enable the realization of heterojunction devices. By controlled dissolution of a poly(acrylic acid) film, on which the OSC films were grown by PVD, they can be released and transferred onto arbitrary substrates. OSC crystal quality and optical anisotropy are preserved during the transfer process. By transferring OSC nanosheets (p-type) onto prefabricated electrodes and TMD monolayers (n-type), we fabricate and characterize various electronic devices including unipolar, ambipolar and antiambipolar field-effect transistors. Such vdW p-n heterojunction devices open up a wide range of possible applications ranging from ultrafast photodetectors to conformal electronics.

scholarly journals A Perspective on the Application of Spatially Resolved ARPES for 2D Materials

2018 ◽  
Author(s):  
Mattia Cattelan ◽  
Neil Fox
Keyword(s):  
Electronic Band Structure ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Electronic Band ◽  
Preparation Methods ◽  
2D Material ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Spatially Resolved ◽  
Metal Dichalcogenides ◽  
Future Direction

In this paper a perspective on the application of spatially- and Angle- Resolved PhotoEmission Spectroscopy (ARPES) for the study of two-dimensional (2D) materials is presented. ARPES allows the direct measurement of the electronic band structure of materials generating extremely useful insights into their electronic properties. The possibility to apply this technique to 2D materials is of paramount importance because these ultrathin layers are considered fundamental for future electronic, photonic and spintronic devices. In this review an overview of the technical aspects of spatially localized ARPES is given along with a description of the most advanced setups for laboratory and synchrotron-based equipment. This technique is sensitive to the lateral dimensions of the sample, therefore a discussion on the preparation methods of 2D material is presented. Some of the most interesting results obtained by ARPES are reported in three sections including: graphene, transition metal dichalcogenides (TMDCs) and 2D heterostructures. Graphene has played a key role in ARPES studies because it inspired the use of this technique with other 2D materials. TMDCs are presented for their peculiar transport, optical and spin properties. Finally, the section featuring heterostructures highlights a future direction for research into 2D material structures.

Probing biexciton in monolayer WS2 through controlled many-body interaction

2D Materials ◽  
2021 ◽  
Author(s):  
Suman Chatterjee ◽  
Sarthak Das ◽  
Garima Gupta ◽  
Kenji Watanabe ◽  
Takashi Taniguchi ◽  
...  
Keyword(s):  
Radiative Recombination ◽  
Transition Metal Dichalcogenides ◽  
Excitation Power ◽  
Equation Model ◽  
Final States ◽  
Many Body ◽  
Time Resolved ◽  
Spectral Separation ◽  
Metal Dichalcogenides ◽  
Time Resolved Photoluminescence

Abstract The monolayers of semiconducting transition metal dichalcogenides host strongly bound excitonic complexes and are an excellent platform for exploring many-body physics. Here we demonstrate a controlled kinetic manipulation of the five-particle excitonic complex, the charged biexciton, through a systematic dependence of the biexciton peak on excitation power, gate voltage, and temperature using steady-state and time-resolved photoluminescence (PL). With the help of a combination of the experimental data and a rate equation model, we argue that the binding energy of the charged biexciton is less than the spectral separation of its peak from the neutral exciton. We also note that while the momentum-direct radiative recombination of the neutral exciton is restricted within the light cone, such restriction is relaxed for a charged biexciton recombination due to the presence of near-parallel excited and final states in the momentum space.

scholarly journals Optically initialized robust valley-polarized holes in monolayer WSe2

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Wei-Ting Hsu ◽  
Yen-Lun Chen ◽  
Chang-Hsiao Chen ◽  
Pang-Shiuan Liu ◽  
Tuo-Hung Hou ◽  
...  
Keyword(s):  
Transition Metal ◽  
Low Temperatures ◽  
Room Temperature ◽  
Optical Pumping ◽  
Transition Metal Dichalcogenides ◽  
Kerr Rotation ◽  
Time Resolved ◽  
Recombination Lifetime ◽  
Valley Polarization ◽  
Metal Dichalcogenides

Abstract A robust valley polarization is a key prerequisite for exploiting valley pseudospin to carry information in next-generation electronics and optoelectronics. Although monolayer transition metal dichalcogenides with inherent spin–valley coupling offer a unique platform to develop such valleytronic devices, the anticipated long-lived valley pseudospin has not been observed yet. Here we demonstrate that robust valley-polarized holes in monolayer WSe2 can be initialized by optical pumping. Using time-resolved Kerr rotation spectroscopy, we observe a long-lived valley polarization for positive trion with a lifetime approaching 1 ns at low temperatures, which is much longer than the trion recombination lifetime (∼10–20 ps). The long-lived valley polarization arises from the transfer of valley pseudospin from photocarriers to resident holes in a specific valley. The optically initialized valley pseudospin of holes remains robust even at room temperature, which opens up the possibility to realize room-temperature valleytronics based on transition metal dichalcogenides.

Sign in / Sign up

Export Citation Format

Share Document