A5000875788- MXene and MAX Phase Materials
- 2D Materials and Applications
- Semiconductor materials and devices
- Ferroelectric and Negative Capacitance Devices
- Graphene research and applications
- Chalcogenide Semiconductor Thin Films
- ZnO doping and properties
- Thin-Film Transistor Technologies
- Advanced Photocatalysis Techniques
- Perovskite Materials and Applications
- Supercapacitor Materials and Fabrication
- GaN-based semiconductor devices and materials
- Fuel Cells and Related Materials
- Optical Coatings and Gratings
- Ga2O3 and related materials
- Plasma Diagnostics and Applications
- Advanced Thermoelectric Materials and Devices
- Advancements in Battery Materials
- Topological Materials and Phenomena
- Electronic and Structural Properties of Oxides
- Advanced Memory and Neural Computing
- Advanced Sensor and Energy Harvesting Materials
- Anodic Oxide Films and Nanostructures
- Diamond and Carbon-based Materials Research
- Metal and Thin Film Mechanics
National Academy of Sciences
2024
National Academies of Sciences, Engineering, and Medicine
2024
National Research Council Canada
2024
University of Virginia
2018-2023
University of Southern California
2021
Dalian Jiaotong University
2021
McCormick (United States)
2018
University of the Philippines Diliman
2017
Controlled oxygen plasma exposure of multilayer WSe2 can modulate the carrier type field effect transistors. XPS shows with increased exposure, top layer(s) oxidizes to amorphous WO(x−3) layer-by-layer a high degree controllability as both single or 2 layers be transformed. A systematic study Raman and photoluminescence signatures clearly demonstrate processing times necessary selectively oxidized 1 exfoliated flakes. devices exposed in channel regions experience an increase p-type...
Atmospheric and long-term aging effects on electrical properties of WSe2 transistors with various thicknesses are examined. Although countless published studies report transition-metal dichalcogenide materials, many not attentive to testing environment or age samples, which we have found significantly impacts results. Our as-fabricated exfoliated pristine devices predominantly n-type, is attributed selenium vacancies. Transfer characteristics measured in air then vacuum reveal physisorbed...
Bi2Se3 was synthesized by a room-temperature deposition technique and successive ionic layer adsorption reaction (SILAR) method with the aim to understand formation, crystallinity, optical properties, energy band structure of this material. The morphology found change from nanoparticles that nanocluster network increasing SILAR cycles. crystalline as-prepared determined grazing-incidence X-ray diffraction (GI-XRD) pattern have mixed metastable orthorhombic rhombohedral phases which further...
Abstract Ferroelectric phase stability in hafnium oxide is reported to be influenced by factors that include composition, biaxial stress, crystallite size, and oxygen vacancies. In the present work, ferroelectric performance of atomic layer deposited Hf 0.5 Zr O 2 (HZO) prepared between TaN electrodes are processed under conditions induce variable stresses evaluated. The post‐processing stress states HZO films reveal no dependence on as‐deposited adjacent electrodes. All maintain tensile...
Abstract Tailoring the electrical transport properties of two-dimensional transition metal dichalcogenides can enable formation atomically thin circuits. In this work, cyclic hydrogen and oxygen plasma exposures are utilized to introduce defects oxidize MoS 2 in a controlled manner. This results sub-stochiometric MoO 3− x , which transforms semiconducting behavior metallic conduction. To demonstrate functionality, single flakes were lithographically oxidized using electron beam lithography...
A thorough understanding of native oxides is essential for designing semiconductor devices. Here, we report a study the rate and mechanisms spontaneous oxidation bulk single crystals ZrSxSe2–x alloys MoS2. oxidize rapidly, increases with Se content. Oxidation basal surfaces initiated by favorable O2 adsorption proceeds mechanism Zr–O bond switching, that collapses van der Waals gaps, facilitated progressive redox transitions chalcogen. The rate-limiting process formation out-diffusion SO2....
In the present work, impact of ZrO2 gate dielectric thickness on electrical performance TiO2 thin film transistors (TFTs) is systematically investigated. Exhaustive measurements TFTs, metal–insulator–metal, and metal–oxide–semiconductor capacitors are carried out with varying dielectrics different thicknesses. It found that possesses an outstanding scalability, providing reliable properties under ultrathin physical 5 nm, while further reduction in would lead to a breakdown indicating...
We reported high performance anatase-TiO2 thin film transistors with a two-step oxidized TiO2 channel (O2 annealing and N2O plasma treatment) O2 enhanced atomic layer-deposited ZrO2 gate dielectric. The using 60 nm as the active exhibited steep subthreshold swing of 112 mV dec−1 on/off current ratio 1.4 × 108. superior performances, achieved by oxidizing process utilization high-k dielectric, show their great potential to be applied in future electronic optical systems, such active-matrix...
In this letter, we report ultrathin-body(~15 nm) TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> thin film transistors (TFTs) with unprecedented electrical performance: ON-current density (I xmlns:xlink="http://www.w3.org/1999/xlink">on</sub> ) of 16.7 mA/mm, ON/OFF current ratio xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> /I xmlns:xlink="http://www.w3.org/1999/xlink">OFF</sub> 1.2 × 10 <sup...
We report on the experimental determination of electron–electron conductance at Au/TiOx interfacial regions and electron–phonon coupling thin TiOx layers for x = 0–2.62. Our study demonstrates that electronic energy transport mechanisms metal/metal oxide interfaces are enhanced through metallic defects lead to band alignment between metal (in our case, Au TiOx). Electronic heat processes interrogated via a pump/probe technique, utilizing sub-picosecond laser pulses monitor ultrafast...
Transition metal dichalcogenides (TMDCs), such as semiconducting WSe2, are typically interfaced with a high-quality dielectric layer in device applications. The unreactive basal plane of TMDCs makes the standard technique for deposition oxides, atomic (ALD), challenging on TMDC surfaces. In this work, we make use atmospheric ultraviolet–ozone (UV-O3) exposure WSe2 to functionalize its surface and promote uniform ALD HfO2. We report two classifications depending UV-O3 time. Low exposures do...
The chemical interaction between Ti and graphene is of significant interest for engineering low-resistance electrical contacts. To study the interface chemistry, sequential depositions are performed on both as-received ultrahigh-vacuum (UHV)-annealed chemical-vapor-deposition-grown samples. In situ X-ray photoelectron spectroscopy (XPS) reveals no experimental evidence reaction with at room temperature or after heating to 500 °C. presence TiC state instead attributed reactions background...
To further the present understanding of growth conditions on quality transition metal dichalcogenide (TMDC) thin films grown by molecular beam epitaxy (MBE), we study effect temperature and chalcogento- flux ratio chemical composition surface morphology synthesized WSe2 films. In-situ X-ray photoelectron spectroscopy (XPS) is performed to analyze intrinsic material prior atmospheric exposure ex-situ atomic force microscopy (AFM) employed grown, sub-monolayer We find that both low high ranges...
Efficient and uniform Aluminum-based broadband mirrors are essential components for far-ultraviolet (FUV) astronomy. Plasma-enhanced atomic layer deposition (PEALD) is a low temperature, highly conformal coating process that has previously been demonstrated to produce high quality AlF<sub>3</sub> films, although little reported on their performance in FUV applications. An ongoing collaboration between the US Naval Research Laboratory (NRL) NASA Goddard Space Flight Center (GSFC) focuses...
In this study, we demonstrate the feasibility of spray-depositing exfoliated graphene on flexible polyimide (PI) and rigid (soda lime glass) substrates for optoelectronic applications. The water contact angles increased by 13% (for PI) 49% when surfaces are pretreated with hexamethyldisiloxane, which significantly improved adhesion films. Raman spectral analyses confirmed a minimum 15 maximum 23 layers deposited substrates. After deposition, films were exposed to 13.56 MHz radio-frequency...
The integration of any new material into device architectures necessarily requires interfaces with dissimilar materials. In the case semiconducting transition metal dichalcogenide (TMDCs) WSe2 interface a gate dielectric is extremely important. Presented will be our work on two approaches to integration. first considers direct growth and insulating substrate. Here we consider impact itself. second approach investigate deposition dielectrics by atomic layer epitaxy onto focus enhancing...