Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session M71: Optoelectronic and Device Applications of 2D MaterialsFocus Recordings Available
|
Hide Abstracts |
Sponsoring Units: DMP Chair: Pengpeng Zhang, Michigan State University Room: Hyatt Regency Hotel -Jackson Park C |
Wednesday, March 16, 2022 8:00AM - 8:36AM |
M71.00001: Phase transition in two dimensional materials and their optical applications Invited Speaker: Ying Wang The discovery and control of new phases of matter is central for materials research. The emergency of atomically thin 2D materials allows the study of phase transition at 2D limit and benefits the development of new phase transition engineering. In this talk, we will discuss multiple phase transition mechanisms. Phase transition can happen interlayer or intralayer in 2D system. Interlayer is governed by covalent bond and intralayer is determined by van der Waals force. We will cover different engineering approaches to control phase transition in interlayer and intralayer respectively. More interestingly, engineering intralayer interaction becomes one effective approach to control stacking orders, one unique structural degree of freedom in 2D materials. Then we will show our recent demonstration on optoelectronic devices based on those new discovered phase transition. |
Wednesday, March 16, 2022 8:36AM - 8:48AM |
M71.00002: Investigation of 2D-material based devices with as-grown metal contacts Norah Aldosari, Maryam Bizhani, William Poston, Gregory Jensen, Eric Stinaff Many 2D transition metal dichalcogenides (TMD) materials are considered ideal candidates for optical and electronic devices however, high-quality consistent electrical contacting is challenging. We will describe a process for forming as-grown contacts to thin film TMDs and present measurements investigating the underlying growth mechanisms and contact properties. TMDs such as MoS2 were fabricated using a chemical vapor deposition (CVD) process on substrates with existing transition metal contacts which serve as both source material and self-forming contacts to the TMD material. Optical characterization shows high quality material. Electrical characterization of as-grown MoS2 based devices typically reveals a metal-semiconductor-metal (MSM) Schottky contact, however, with significant variation. To investigate this variability, we performed cross-sectional SEM imaging as well as deposited post-growth contacts using standard techniques on material with as-grown contacts to help isolate the underlying characteristics of the contacts. These results indicate a complex formation process often resulting in a potentially controllable thin metal-oxide layer. This understanding provides a path to tune the growth process to form consistent high-quality contacts in a scalable manner. |
Wednesday, March 16, 2022 8:48AM - 9:00AM |
M71.00003: Thermal Annealing Effects on Naturally Contacted Monolayer MoS2 Maryam Bizhani, Ruhi Thorat, William Poston, Thushan E Wickramasinghe, Shrouq H Aleithan, Greg M Jensen, Eric Stinaff We study the effects of postgrowth processing including thermal annealing and laser annealing on the quality, crystallinity, and optical properties of monolayer molybdenum di-sulfide (MoS2) which is grown using a novel chemical vapor deposition (CVD) method. In this CVD process a thin layer of metal oxide which is formed on bulk lithographically defined molybdenum patterns serves as the nucleation precursor. The preliminary photoluminescence (PL) measurements on monolayer MoS2 have shown a blueshift in the lower energy peak after annealing. In addition, the PL map became more uniform up to an annealing temperature of 300°C. At higher temperatures, isolated monolayers begin to crack along the grain boundaries, which leads to variations in luminescence. We also performed an optical investigation of thermal annealing effects on monolayer MoS2 anchored to the molybdenum patterns via PL measurements. Our observation showed that after an annealing temperature of 200°C, the anchored materials became susceptible to laser ablation. This observation inspired us to further study possible laser processing for localized thermal treatment of the materials. |
Wednesday, March 16, 2022 9:00AM - 9:12AM |
M71.00004: Environment-dependent Interlayer Exciton Behaviors in Atomically Thin Hybrid Heterostructures Jong Hyun Choi, Jaehoon Ji Interlayer excitons (IX), formed in 2D transition metal dichalcogenide (TMD) heterostructures, have attracted significant attention to realize future optoelectronics such as spintronics and excitonic devices. Despite the advances, environmental effects, including dielectric screening, separation length of electron-hole pair in IX and interlayer charge transfer, are not fully understood. To better understand the effects, we introduce organic-layer-embedded MoS2/organic/WSe2 hybrids. The inserted molecular layer enhances the dielectric screening with a reduced dielectric constant and an increased separation length, thereby reducing IX binding energy. In addition, the interlayer charge transfer in the hybrid is regulated by the nature of the organic layer. The layer forming type-II junctions with TMDs converts the charge transfer pathway from tunneling to band-assisted transfer. This allows an energetically favorable transfer, facilitating a greater population of IX. As a result, a stronger IX-IX interaction is observed, which consequently leads to the higher energy of IX in the hybrid. Lastly, the IX formation may also be prohibited by introducing electron or hole trapping organic layers. This work may provide a deeper understanding on IX for realizing IX-based applications. |
Wednesday, March 16, 2022 9:12AM - 9:24AM |
M71.00005: Patterned Regrowth of Coherent Lateral Heterojunctions in Transition Metal Dichalcogenides Ce Liang, Jiwoong Park Patterning electronic properties within a single crystalline material provides a foundation for modern information technology. Similar capabilities can be realized in atomically thin two-dimensional (2D) crystals by forming lateral heterostructures with coherent, defect-free, lattice connections. In this talk, I will discuss how one can produce such 2D films with spatially designable coherent heterointerfaces based on multiple transition metal dichalcogenide (TMD) monolayers. For this, we combine three advanced techniques into an integrated procedure: patterned regrowth, resist-free patterning, and precisely controlled metalorganic chemical vapor deposition. The resulting structures are then characterized by Raman and TEM, which demonstrated lateral epitaxy at the patterned boundaries. I will also present the results of electrical transport measurements from these junctions. Our approach could lead to the generation of high-performance electronic and optoelectronic devices in the atomically thin limit. |
Wednesday, March 16, 2022 9:24AM - 9:36AM |
M71.00006: Compositional dependence of the optical and electronic properties of single layer MoS2-WS2 alloys Juan M Marmolejo-Tejada, Nicholas Borys, Martin A Mosquera Recent studies on atomically thin lateral heterostructures have demonstrated the formation of complex interfaces that could be exploited for tuning the physical properties of 2D semiconductors for optoelectronic applications. In order to understand the compositional dependence of the optical and electronic properties in these interfaces, tip-enhanced Raman scattering (TERS) imaging and spectroscopy have been used to characterize 2D lateral heterostructures at different sites across the interface, showing a continuous evolution of the Raman active modes when transitioning from one pristine material to the other. Here, we use density functional theory (DFT) for calculating the evolution of vibrational modes, non-resonant Raman spectra, optical absorption and electronic structure of single-layer MoS2, WS2 and MoxW1-xS2 alloys. We further explore the role of S vacancies in the appearance of a defect mode in these systems and its evolution, allowing a direct comparison to recent non-resonant Raman measurements on analogous systems. Lastly, we anticipate that the same computational approach can be useful for predicting the compositional-dependent properties of additional lateral heterostructures, and providing a valuable resource for quantitatively interpreting state-of-the-art characterization measurements. |
Wednesday, March 16, 2022 9:36AM - 9:48AM |
M71.00007: MoS2 Hybrids with Intercalated Zerovalent Metals for Optoelectronics Ashwin Ramasubramaniam, Chen Stern, Avraham Twitto, Rafi Snitkoff, Yafit Fleger, Sabyasachi Saha, Loukya Bodipatti, Akash Jain, Mengjing Wang, Kristie J Koski, Francis L Deepak, Doron Naveh The intercalation of layered compounds is a promising route for scalable synthesis of 2D heterostructures with novel emergent optoelectronic properties. Here, we investigate, via first principles calculations, the intercalation of zerovalent metals within the van der Waals gap of bulk MoS2. Specifically, we focus on a novel Cu-MoS2 hybrid that accommodates uniform, continuous 2D layers of metallic Cu within the vdW gap of MoS2. We study the evolution of the Cu-MoS2 hybrid with increasing Cu content and examine the consequences for intercalation energetics and optoelectronic properties as the intercalated Cu evolves from disordered clusters to contiguous layers. We identify an emergent plasmon resonance (~1eV) that is unique to the Cu-MoS2hybrid, arising from resonant 2D Cu states within the MoS2 band gap. Our calculations are shown to be in good agreement with experiments and help explain the enhanced infrared absorption of the Cu-MoS2 hybrids. We also compare and contrast the Cu-MoS2 hybrid with Sn-MoS2 hybrids that are less amenable to complete intercalation but can nevertheless display enhanced infrared absorption with the intercalation of small Sn clusters. Overall, our results indicate that intercalation of zerovalent metals in layered materials offers a facile and scalable approach for designing hybrid 2D heterostructures with tunable optoelectronic properties for device applications. |
Wednesday, March 16, 2022 9:48AM - 10:00AM |
M71.00008: Micropatterned PDMS stamps for spatially selective dry transfer of exfoliated flakes Charles F Yang, John W Lyons, Benjamin M Hunt PDMS+polymer transfer slides are one of the primary tools for making van der Waals heterostructures from exfoliated flakes using a dry transfer process. However, such transfer slides are typically made from either flat stamps or round droplets of PDMS, whose macroscopic size makes it difficult to selectively pick up flakes in a crowded environment. A ready solution can be drawn from the field of microfluidics, where micropatterned SU-8 or silicon are used as molds to form fine details on the surface of PDMS stamps for techniques such as microcontact printing. We will discuss the efficacy of using such PDMS micropatterning to construct ten-micron scale features to improve the spatial selectivity of the dry transfer process. |
Wednesday, March 16, 2022 10:00AM - 10:12AM |
M71.00009: Robotically Manufactured Complex van der Waals Heterostructures for Interlayer-Angle-Controlled Combinatorial Solids Andrew Ye, Andrew J Mannix, Suk Hyun Sung, Ariana Ray, Fauzia Mujid, Chibeom Park, Myungjae Lee, Jong-Hoon Kang, Robert T Shreiner, Alexander A High, David A Muller, Robert Hovden, Jiwoong Park Advancements in the production & processing of 2D materials (2DMs) have been building towards creating complex inter/intra-layer solids, where each specifically-shaped constituent layer amalgamates into a structure that controls X/Y/Z/θ in totality. This is the same design paradigm used in evaporated films for conventional integrated circuits — we use this philosophy to develop our new technique for manufacturing 2DMs combinatorial solids. The technique has three steps: wafer-scale synthesis, polymer-contact-free patterning, and high vacuum dry-transfer automation. We use this to assemble designer van der Waals solids where each spatial region programmatically alters layer number & permuted composition. These solids function as optical spectroscopy assays, where we can study incremental changes in optical response. This technique achieves an unprecedented stacking rate (30 layers/hr) for large-area layers (100 μm)2 with few-μm X/Y resolution and <0.2° angle precision. We can also fabricate twisted N-layers; in one instance we observe atomic reconstruction of twisted 4-layer WS2 at twist angles of ≥4°. Compatibility with pre-fabricated electrodes & multiplexed assembly also imply this technique can parallel manufacture complex electrical circuits without ever breaking vacuum. |
Wednesday, March 16, 2022 10:12AM - 10:24AM |
M71.00010: Liquid-phase exfoliated MoS2 nanosheets doped with p-type transition metals: a comparative analysis of photocatalytic and antimicrobial potential combined with density functional theory Ali Raza In order to enhance its photocatalytic properties, the host material was doped with p-type transition metals (Ag, Co, Bi, and Zr). The hydrothermal technique was used to produce samples doped with 7.5 wt% transition metals. Raman analysis was undertaken to identify molecular vibrations. The A1g mode in Raman spectra consistently showed a blueshift in all samples and the E12g mode was only slightly affected, which is evidence of the p-type doping in the MoS2 nanosheets. Diverse morphologies were observed with a non-uniform distribution of the dopant. Photocatalytic action of the TM-doped products effectively degraded MB concentrations of up to 94 % (for Ag-MoS2). Moreover, results from first-principles calculations indicate that substitutional doping of TM atoms is indeed advantageous. DFT confirmed that doping with Ag, Co, Bi, and Zr leads to a decrease in the bandgap to a certain degree, in which the conduction band edge shifts toward lower energy, while the valence band shifts closer to the high energy end. It can be concluded that Ag, Co, and Bi impurities can lead to beneficial p-type doping in MoS2 monolayered structures. With regards to doping with Zr, the acceptor levels are formed above the edge of the valence band, revealing an introduction of the p-type character. |
Wednesday, March 16, 2022 10:24AM - 10:36AM |
M71.00011: Giant Photoresponse enhancement in mixed-dimensional van der Waals heterostructure through dielectric engineering VRINDA N P The reduced dielectric screening in the out-of-plane direction, makes 2D materials sensitive to the surrounding environment, offering a unique platform with greatly tunable optoelectronic properties. Large exciton binding energy in 2D materials limits their photogeneration efficiency. The strong electric field generated at a pn junction will help in separating these strongly bound electron-hole pairs. Here, the present study demonstrates how engineering the surrounding dielectric environment would facilitate a mixed dimensional van der Waals p-n junction to improve the photoresponse to a great extent. A 3D silicon- 2D monolayer MoS 2 heterostructure was fabricated as a model system. A |
Wednesday, March 16, 2022 10:36AM - 10:48AM |
M71.00012: Transistors based on graphene nanoribbon triple junctions Kristians Cernevics, Oleg V Yazyev Bottom-up chemical self-assembly of graphene nanoribbons (GNRs) has opened the possibility for all-graphene integrated circuits of nanoscale dimensions. These versatile building blocks exhibiting a broad range of controllable electronic properties have been considered, for example, as potential interconnects or spin filters, but more complex components are not yet conceptualized. In this work, we envisage in-plane triple GNR junctions as potential next-generation transistors. Considering the three leads as either "source", "drain" or "gate", we investigate the transport properties of triple junctions with the help of tight-binding(TB) models, density-functional theory (DFT), and Green's function approach. Utilizing experimentally synthesized chevron-GNR triple junction as a basis, we introduce "bite" defects – the most common defect in chevron GNR synthesis – to enhance the transport between the source and drain leads, while suppressing the transmission to the gate lead. Next, we investigate the effects on the transmission by, first, a simple TB model, where a locally placed charge simulates the electric field and, second, by applying the gate voltage in DFT calculations. |
Wednesday, March 16, 2022 10:48AM - 11:00AM |
M71.00013: Intercalation-Enhanced Light-Matter Interactions in MoS2: Comparing Copper to Tin Doron Naveh, Chen Stern, Saha Sabyasachi, Leonard D Francis, Akash Jain, Kristie J Koski, Avraham Twitto, Ashwin Ramasubramaniam Intercalation spans a vast space for modifying the properties of materials and provides a laboratory for studying fundamental chemical and physical phenomena on the atomic scale. Here, we present the cases of zero-valent copper and tin intercalation in MoS2 as employed by the Koski method. We show that in both cases the host MoS2 remains semiconducting even at the limit of high metal content. The spectrally broad and high cross section of the metals enhances the interaction of intercalated MoS2 with light and its photodetection capabilities. This results in highly responsive devices at a broad spectral range. However, the two cases fall under different enhancement mechanisms, representing the difference in the atomic species properties as well as the packing structure and density of the intercalants within the van der Waals gap: while tin organizes in small clusters, copper intercalants organize in continuous, extended layers between those of MoS2. While copper features a strong plasmon resonance, tin clusters tend to ionize by contributing electrons to the conduction band of the MoS2 hybrid. We also compare the spectral response to the two hybrids, showing a redshift towards the infrared in the photoconductivity of Sn:MoS2. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700