scholarly journals Thermal rectification on asymmetric suspended graphene nanomesh devices

Nano Futures ◽  
2021 ◽  
Author(s):  
Fayong Liu ◽  
Manoharan Muruganathan ◽  
Yu Feng ◽  
Shinichi Ogawa ◽  
Yukinori Morita ◽  
...  
Keyword(s):  
Thermal Transport ◽  
High Performance ◽  
Ion Beam ◽  
Phononic Crystal ◽  
Rectification Ratio ◽  
Suspended Graphene ◽  
Thermal Rectification ◽  
Helium Ion ◽  
Graphene Nanomesh ◽  
20 Nm

Abstract The graphene-based thermal rectification is investigated by measuring the thermal transport properties on asymmetric suspended graphene nanomesh devices. Sub-10 nm periodic nanopore phononic crystal structure is successfully patterned on the half area of the suspended graphene by the helium ion beam milling technology. The “differential thermal leakage” method is developed for thermal transport measurement without being disturbed by the electron current leakage through the suspended graphene bridge. Up to 60 % thermal rectification ratio is observed in a typical device with a nanopore pitch of 20 nm. By increasing the nanopore pitch in a particular range, the thermal rectification ratio shows an increment. However, this ratio is degraded by increasing the environmental temperature. This experiment preliminary shows a promising way to develop a high-performance thermal rectifier by using a phononic crystal to introduce the asymmetry on homogenous material.

Quantum dot formation on suspended graphene nanomesh by helium ion beam milling technology

2021 ◽  
Author(s):  
Fayong Liu ◽  
Manoharan Muruganathan ◽  
Shinichi Ogawa ◽  
Yukinori Morita ◽  
Zhongwang Wang ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Ion Beam ◽  
Suspended Graphene ◽  
Helium Ion ◽  
Graphene Nanomesh

scholarly journals Conductance Tunable Suspended Graphene Nanomesh by Helium Ion Beam Milling

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 387 ◽  
Author(s):  
Fayong Liu ◽  
Zhongwang Wang ◽  
Soya Nakanao ◽  
Shinichi Ogawa ◽  
Yukinori Morita ◽  
...  
Keyword(s):  
Thermal Activation ◽  
Ion Beam ◽  
Thermal Activation Energy ◽  
Exponential Relationship ◽  
New Approach ◽  
Suspended Graphene ◽  
Helium Ion ◽  
Defective Region ◽  
Graphene Nanomesh ◽  
The Individual

This paper demonstrates that the electrical properties of suspended graphene nanomesh (GNM) can be tuned by systematically changing the porosity with helium ion beam milling (HIBM). The porosity of the GNM is well-controlled by defining the pitch of the periodic nanopores. The defective region surrounding the individual nanopores after HIBM, which limits the minimum pitch achievable between nanopores for a certain dose, is investigated and reported. The exponential relationship between the thermal activation energy (EA) and the porosity is found in the GNM devices. Good EA tuneability observed from the GNMs provides a new approach to the transport gap engineering beyond the conventional nanoribbon method.

Structurally Controlled Large-Area 10 nm Pitch Graphene Nanomesh by Focused Helium Ion Beam Milling

2018 ◽  
Vol 10 (12) ◽  
pp. 10362-10368 ◽  
Author(s):  
Marek Edward Schmidt ◽  
Takuya Iwasaki ◽  
Manoharan Muruganathan ◽  
Mayeesha Haque ◽  
Huynh Van Ngoc ◽  
...  
Keyword(s):  
Ion Beam ◽  
Large Area ◽  
Helium Ion ◽  
Graphene Nanomesh

Linear and Nonlinear Thermal Transport in Graphene: Molecular Dynamics Simulations

2011 ◽  
Vol 1347 ◽  
Author(s):  
Bo Qiu ◽  
Yan Wang ◽  
Xiulin Ruan
Keyword(s):  
Molecular Dynamics ◽  
Thermal Transport ◽  
Graphene Nanoribbons ◽  
Ballistic Transport ◽  
Thermal Conductance ◽  
Md Simulations ◽  
Spectral Energy ◽  
Suspended Graphene ◽  
Thermal Rectification ◽  
Dynamics Simulations

AbstractIn this work, we perform molecular dynamics (MD) simulations to study the linear thermal transport in suspended graphene and the nonlinear thermal transport phenomena in graphene nanoribbons (GNR). We use spectral energy density analysis to quantitatively address the relative importance of different types of phonon in thermal transport in suspended graphene. Negative differential thermal conductance (NDTC) and thermal rectification in graphene nanoribbons have been studied using nonequilibrium molecular dyanmics simulations. Ballistic transport regime, sufficient temperature nonlinearity and asymmetry are found to be necessary conditions for the onset of these behaviors.

Low Energy Ar Ion Milling of FIB TEM Specimens from 14 nm and Future FinFET Technologies

2018 ◽  
Author(s):  
C.S. Bonifacio ◽  
P. Nowakowski ◽  
M.J. Campin ◽  
M.L. Ray ◽  
P.E. Fischione
Keyword(s):  
Field Effect Transistor ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Specimen Preparation ◽  
Ion Milling ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Effect Transistor ◽  
20 Nm ◽  
Argon Ion

Abstract Transmission electron microscopy (TEM) specimens are typically prepared using the focused ion beam (FIB) due to its site specificity, and fast and accurate thinning capabilities. However, TEM and high-resolution TEM (HRTEM) analysis may be limited due to the resulting FIB-induced artifacts. This work identifies FIB artifacts and presents the use of argon ion milling for the removal of FIB-induced damage for reproducible TEM specimen preparation of current and future fin field effect transistor (FinFET) technologies. Subsequently, high-quality and electron-transparent TEM specimens of less than 20 nm are obtained.

Large-Scale Focused Helium Ion Beam Lithography

2021 ◽  
Vol 31 (5) ◽  
pp. 1-4
Author(s):  
Jay C. LeFebvre ◽  
Shane A. Cybart
Keyword(s):  
Large Scale ◽  
Ion Beam ◽  
Ion Beam Lithography ◽  
Helium Ion

scholarly journals High performance, electroforming-free, thin film memristors using ionic Na0.5Bi0.5TiO3

2021 ◽  
Vol 9 (13) ◽  
pp. 4522-4531
Author(s):  
Chao Yun ◽  
Matthew Webb ◽  
Weiwei Li ◽  
Rui Wu ◽  
Ming Xiao ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Resistive Switching ◽  
Growth Temperature ◽  
High Performance ◽  
20 Nm

Interfacial resistive switching and composition-tunable RLRS are realized in ionically conducting Na0.5Bi0.5TiO3 thin films, allowing optimised ON/OFF ratio (>104) to be achieved with low growth temperature (600 °C) and low thickness (<20 nm).

scholarly journals Decoupling electron and phonon transport in single-nanowire hybrid materials for high-performance thermoelectrics

2021 ◽  
Vol 7 (20) ◽  
pp. eabe6000
Author(s):  
Lin Yang ◽  
Madeleine P. Gordon ◽  
Akanksha K. Menon ◽  
Alexandra Bruefach ◽  
Kyle Haas ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Electrical Transport ◽  
High Performance ◽  
Figure Of Merit ◽  
Phonon Transport ◽  
Core Shell ◽  
Nanowire Diameter ◽  
High Performing ◽  
Polycrystalline Thin Films

Organic-inorganic hybrids have recently emerged as a class of high-performing thermoelectric materials that are lightweight and mechanically flexible. However, the fundamental electrical and thermal transport in these materials has remained elusive due to the heterogeneity of bulk, polycrystalline, thin films reported thus far. Here, we systematically investigate a model hybrid comprising a single core/shell nanowire of Te-PEDOT:PSS. We show that as the nanowire diameter is reduced, the electrical conductivity increases and the thermal conductivity decreases, while the Seebeck coefficient remains nearly constant—this collectively results in a figure of merit, ZT, of 0.54 at 400 K. The origin of the decoupling of charge and heat transport lies in the fact that electrical transport occurs through the organic shell, while thermal transport is driven by the inorganic core. This study establishes design principles for high-performing thermoelectrics that leverage the unique interactions occurring at the interfaces of hybrid nanowires.

Phase-Shifting Electron Holography for Accurate Measurement of Potential Distributions in Organic and Inorganic Semiconductors

Microscopy ◽  
2020 ◽  
Author(s):  
Kazuo Yamamoto ◽  
Satoshi Anada ◽  
Takeshi Sato ◽  
Noriyuki Yoshimoto ◽  
Tsukasa Hirayama
Keyword(s):  
High Performance ◽  
Focused Ion Beam ◽  
Phase Measurement ◽  
Ion Beam ◽  
Functional Materials ◽  
Phase Shifting ◽  
Future Research ◽  
Electron Holography ◽  
Preparation Technique ◽  
Inorganic Semiconductors

Abstract Phase-shifting electron holography (PS-EH) is an interference transmission electron microscopy technique that accurately visualizes potential distributions in functional materials, such as semiconductors. In this paper, we briefly introduce the features of the PS-EH that overcome some of the issues facing the conventional EH based on Fourier transformation. Then, we present a high-precision PS-EH technique with multiple electron biprisms and a sample preparation technique using a cryo-focused-ion-beam, which are important techniques for the accurate phase measurement of semiconductors. We present several applications of PS-EH to demonstrate the potential in organic and inorganic semiconductors and then discuss the differences by comparing them with previous reports on the conventional EH. We show that in situ biasing PS-EH was able to observe not only electric potential distribution but also electric field and charge density at a GaAs p-n junction and clarify how local band structures, depletion layer widths, and space charges changed depending on the biasing conditions. Moreover, the PS-EH clearly visualized the local potential distributions of two-dimensional electron gas (2DEG) layers formed at AlGaN/GaN interfaces with different Al compositions. We also report the results of our PS-EH application for organic electroluminescence (OEL) multilayers and point out the significant potential changes in the layers. The proposed PS-EH enables more precise phase measurement compared to the conventional EH, and our findings introduced in this paper will contribute to the future research and development of high-performance semiconductor materials and devices.

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