Article
Chemistry, Multidisciplinary
Dezhao Huang, Qiangsheng Sun, Zeyu Liu, Shen Xu, Ronggui Yang, Yanan Yue
Summary: The authors developed a tip-enhanced Raman thermometry approach to study thermal transport at nanoscale hotspots and predicted the phonon mean free path through a combination of experiments and simulations.
Article
Multidisciplinary Sciences
Sanchit Deshmukh, Miguel Munoz Rojo, Eilam Yalon, Sam Vaziri, Cagil Koroglu, Raisul Islam, Ricardo A. Iglesias, Krishna Saraswat, Eric Pop
Summary: Resistive random access memory (RRAM) is a crucial technology for digital storage and analog computing, relying on the formation and rupture of nanoscale conductive filaments. By using scanning thermal microscopy, researchers directly measure the temperature of these filaments and find that they can reach up to 1300 degrees C during steady-state operation, while electrode temperatures rarely exceed 350 degrees C. This highlights the importance of thermal engineering for nanoscale RRAM.
Article
Multidisciplinary Sciences
M. Amir Bazrafshan, Farhad Khoeini
Summary: The transport properties of S-shaped graphene structures with different vacancies were studied, and it was found that double vacancies have the best figure of merit. The physical properties of the system can be controlled by adjusting parameters, and lengthening the structure can reduce phononic contribution. Single vacancies are better at distinguishing between electronic thermal conductance and electronic conductance. Vacancy engineering can significantly improve thermoelectric performance.
SCIENTIFIC REPORTS
(2022)
Article
Chemistry, Multidisciplinary
Bryan T. Spann, Joel C. Weber, Matt D. Brubaker, Todd E. Harvey, Lina Yang, Hossein Honarvar, Chia-Nien Tsai, Andrew C. Treglia, Minhyea Lee, Mahmoud I. Hussein, Kris A. Bertness
Summary: With the combination of nanopillars and membranes, the thermal conductivity of thermoelectric materials has been significantly reduced while the electrical conductivity remains unaffected, achieving decoupling of thermoelectric properties. This finding paves the way for high-efficiency solid-state energy recovery and cooling.
ADVANCED MATERIALS
(2023)
Article
Physics, Multidisciplinary
Bin Wei, Qingan Cai, Qiyang Sun, Yaokun Su, Ayman H. Said, Douglas L. Abernathy, Jiawang Hong, Chen Li
Summary: By measuring the Matryoshka phonon dispersions, insights into the anisotropic thermal conductivity of semiconducting alpha-GaN have been gained, showing how phonon topology affects thermal transport in the material. This study demonstrates the importance of understanding lattice dynamics for effective thermal management in electronic devices.
COMMUNICATIONS PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
B. Bommalingaiah, Narayan Gaonkar, R. G. Vaidya
Summary: Theoretical investigation of macroscopic polarization effects on lattice thermal conductivity of GaN reveals significant impact of polarization fields on thermal conductivity, especially from high frequency transverse mode phonons. Numerical calculations show good agreement with experimental reports for thermal conductivity of different dimension samples with and without polarization fields.
Article
Physics, Applied
Hiroko Iguchi, Keita Kataoka, Taishi Kimura, Daigo Kikuta
Summary: We demonstrated the advantage of post-implantation annealing (PIA) in NH3/N-2 for a p-n diode (PND) fabrication, compared to annealing in N-2. NH3/N-2 annealing reduced the leakage current for the PND with a reverse bias and decreased the densities of non-radiative recombination centers and nitrogen vacancy complexes. PIA in NH3/N-2 effectively suppressed the density of implantation induced defects as leakage current sources.
APPLIED PHYSICS EXPRESS
(2022)
Article
Chemistry, Multidisciplinary
Zebin Li, Takatoshi Seto, Yuhua Wang
Summary: To enhance the thermal stability and luminescence performance of red-emitting phosphor, co-doping with rare earth ions is employed. Although co-doping reduces the luminescence intensity, it significantly improves the thermal stability. The nitride phosphor has potential applications in field emission displays due to its high saturation current.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Zhiliang Pan, Yi Tao, Yang Zhao, Matthew L. Fitzgerald, James R. McBride, Lei Zhu, Deyu Li
Summary: The contact thermal resistance between individual boron nitride nanotubes is largely determined by reflection of ballistic phonons, but can be influenced by the presence of a poly(vinylpyrrolidone) interlayer. The interlayer can either enhance or reduce the contact thermal resistance by converting the transport mechanism from ballistic phonon dominated to diffusion through the interlayer. This study provides insights into the design of high thermal conductivity boron nitride nanotube-polymer composites.
Article
Optics
Ekaterina Dementeva, Kseniia N. Orekhova, Marina G. Mynbaeva, Maria Zamoryanskaya
Summary: This paper investigates the cathodoluminescent properties of point defects in bulk GaN samples grown by HVPE technique. The cathodoluminescence spectra of GaN show two broad luminescence bands in the blue and yellow ranges. Each luminescence band is associated with several point defects - luminescence centers with similar spectral positions but different decay times. The paper proposes a technique for estimating the relative content of luminescent centers based on measuring cathodoluminescence intensity dependence on electron beam current density and decay times. Changes in the relative contents of point defects - luminescence centers are determined for different regions of the sample, and the excitation capture efficiency is constant for luminescence centers emitting in the yellow range.
JOURNAL OF LUMINESCENCE
(2022)
Article
Nanoscience & Nanotechnology
H. Zhang, V Piazza, V Neplokh, N. Guan, F. Bayle, S. Collin, L. Largeau, A. Babichev, F. H. Julien, M. Tchernycheva
Summary: The study investigated the origin of electrical inhomogeneities in an array of core-shell InGaN/GaN nanowires and proposed a solution by changing the contact architecture, which led to a significant increase in the yield of emitting nanowires. The impact of a potential barrier at the interface between the nanowire core and the radially grown n-doped layer on the performance of the array was analyzed using multiple scanning techniques.
Article
Materials Science, Multidisciplinary
V. Orlov, A. Y. Polyakov, P. S. Vergeles, E. B. Yakimov, Gyu Cheol Kim, In-Hwan Lee
Summary: The study found that star-of-David-like rosettes can form in p-GaN even at room temperature, while in n-GaN, they require temperatures exceeding 573K. The activation energy for dislocation glide in p-GaN is lower than in n-GaN, resulting in a decrease in peak intensities in dislocated regions.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2021)
Article
Computer Science, Information Systems
Terirama Thingujam, Quan Dai, Eunjin Kim, Jung-Hee Lee
Summary: This study found that in ideal conditions, circular geometry nanowire MOSFET exhibited the best performance, while triangular and hexagonal geometry nanowire MOSFETs were affected by large gate leakage current due to field enhancement at sidewall corners.
Article
Nanoscience & Nanotechnology
Gui Yang, Xiaodong Zhang, Duo Pan, Wei Zhang, Ying Shang, Fengmei Su, Youxin Ji, Chuntai Liu, Changyu Shen
Summary: In this study, highly thermally conductive PVA/BNNS@AgNW composites were fabricated by combining electrospinning and spraying techniques, showing excellent thermal conductivity and electrical insulating properties for potential applications in electrical packaging and thermal management.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Physical
Chun-Lin Su, Kogularasu Sakthivel, Yu-Tsun Yao, Po-Hsun Liao, Ming-Lun Lee, Jinn-Kong Sheu
Summary: This article discusses a new method to improve the water-splitting efficiency of gallium nitride photoelectrodes using alkali-treated NiOx films. The study shows that NiOOH formed on the NiOx/n-GaN surface can act as an electrocatalyst to promote carrier transportation kinetics on GaN photoanodes. By using this method, the photocurrent density is increased, and a significant H-2 production rate is achieved.
ACS APPLIED ENERGY MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
Mohammed Zeghouane, Yamina Andre, Geoffrey Avit, Jihen Jridi, Catherine Bougerol, Pierre-Marie Coulon, Pierre Ferret, Dominique Castelluci, Evelyne Gil, Philip Shields, Vladimir G. Dubrovskii, Agnes Trassoudaine
Article
Nanoscience & Nanotechnology
Magdalena Sola-Garcia, Kelly W. Mauser, Matthias Liebtrau, Toon Coenen, Silke Christiansen, Sophie Meuret, Albert Polman
Summary: Photon bunching in incoherent cathodoluminescence spectroscopy results from the interaction of high-energy electrons with a material, generating multiple photons and revealing key properties of electron-matter excitation. An analytical model has been developed to describe the amplitude and shape of the second order autocorrelation function for continuous and pulsed electron beams, including ultrashort pulses. Experimental data on InGaN/GaN quantum wells show good agreement with the model, providing insights on excitation efficiencies and nonlinear effects.
Article
Engineering, Electrical & Electronic
Hongwei Liu, Xinwei Wang, Pingjuan Niu, Philip Shields, Zanyun Zhang, Xiaoyun Li, Chao Liu, Duxiang Wang
Summary: The research shows that in the growth of InP/InGaAs/InP PIN photodetector material, controlling the diffusion depth of Zn doping in p-InP can affect the high frequency characteristics of the PIN photodiode, providing a new reference for the design of photodiodes and varactors in optical microwave mixed circuits.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2021)
Article
Physics, Applied
S. Meuret, L. H. G. Tizei, F. Houdellier, S. Weber, Y. Auad, M. Tence, H-C Chang, M. Kociak, A. Arbouet
Summary: This study reported time-resolved cathodoluminescence measurements in an ultrafast transmission electron microscope, achieving spatial resolution of 12 nm and temporal resolution of sub-nanoseconds.
APPLIED PHYSICS LETTERS
(2021)
Article
Optics
Pierre Chausse, Philip Shields
Summary: Displacement Talbot Lithography (DTL) is a simple patterning technique for creating periodic sub-micron features, utilizing diffraction and interference effects. By simulating different mask configurations, one can adjust the impact on the Talbot effect to control feature size, uniformity, and contrast in lithography.
Article
Energy & Fuels
Larkin Sayre, Eduardo Camarillo Abad, Phoebe Pearce, Pierre Chausse, Pierre-Marie Coulon, Philip Shields, Andrew Johnson, Louise C. Hirst
Summary: The paragraph discusses the applications and advantages of ultra-thin photovoltaics, as well as the development of a GaAs solar cell with an 80-nm absorber and optical simulations results. Through the use of light management and nanophotonic grating techniques, efficiency improvement and short circuit current increase were successfully achieved.
PROGRESS IN PHOTOVOLTAICS
(2022)
Article
Physics, Applied
G. Naresh-Kumar, P. R. Edwards, T. Batten, M. Nouf-Allehiani, A. Vilalta-Clemente, A. J. Wilkinson, E. Le Boulbar, P. A. Shields, B. Starosta, B. Hourahine, R. W. Martin, C. Trager-Cowan
Summary: We demonstrate a non-destructive approach to understanding the growth modes of a GaN thin film and quantify its residual strains and their effect on optical and electrical properties. We find strain variations near dislocations, and the dislocations organize themselves into a distinctive pattern.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Julien Bosch, Pierre-Marie Coulon, Sebastien Chenot, Marc Portail, Christophe Durand, Maria Tchernycheva, Philip A. Shields, Jesus Zuniga-Perez, Blandine Alloing
Summary: This paper proposes three different strategies, chemical, physical, or thermal etching, to remove the SiGaxNy layer on the sidewalls of GaN core-shell wires, thereby improving their optical quality. Chemical etching with H3PO4 enhances the emissive coverage and luminescence intensity, while removing deep-defect emissions from the high growth temperature.
CRYSTAL GROWTH & DESIGN
(2022)
Article
Chemistry, Multidisciplinary
Chaoqiang Zhang, Ke Gao, Fei Wang, Zhiming Chen, Philip Shields, Sean Lee, Yanqin Wang, Dongyan Zhang, Hongwei Liu, Pingjuan Niu
Summary: This paper investigates the edge strain relaxation of InGaN/GaN MQW micro-pillars. The results show a significant peak wavelength shift between micro-pillar arrays caused by a high range of strain relaxation. Raman spectrum observation and finite element method simulation provide effective verification of the strain relaxation analysis, offering references for the design and analysis of small-size micro-LED devices.
APPLIED SCIENCES-BASEL
(2022)
Article
Chemistry, Multidisciplinary
Mohammed Zeghouane, Gabin Gregoire, Emmanuel Chereau, Geoffrey Avit, Philipp Staudinger, Kirsten E. Moselund, Heinz Schmid, Evelyne Gil, Pierre-Marie Coulon, Philip Shields, Nebile Isik Goktas, Ray R. LaPierre, Agnes Trassoudaine, Yamina Andre
Summary: In this study, vertically oriented GaAs nanowires and microplatelets were grown directly on a patterned SiO2/Si(111) substrate using hydride vapor-phase epitaxy (HVPE). The direct condensation of GaAs on Si was achieved through surface preparation under an As-controlled atmosphere. The growth of GaAs nanowires along the ⟨111⟩B direction with hexagonal cross sections was observed when the hole opening diameter in the SiO2 mask was below 350 nm. Larger apertures resulted in uniform microplatelets. This research highlights the capability of HVPE for selective area growth of GaAs on Si and its potential as a generic heterointegration process for III-V semiconductors on silicon.
CRYSTAL GROWTH & DESIGN
(2023)
Article
Chemistry, Multidisciplinary
Douglas Cameron, Pierre-Marie Coulon, Simon Fairclough, Gunnar Kusch, Paul R. Edwards, Norman Susilo, Tim Wernicke, Michael Kneissl, Rachel A. Oliver, Philip A. Shields, Robert W. Martin
Summary: Existing barriers to efficient deep-UV LEDs can be overcome by utilizing threedimensional nanostructuring instead of planar growth. A hybrid top-down/bottom-up approach was used to create highly uniform AlGaN core-shell nanorods on sapphire, which showed promising features like enhanced doping and improved light extraction efficiency. The nanorods were found to have low turn-on voltages, strongly rectifying behaviors, and short carrier lifetimes, making them suitable for deep-UV-emitting LEDs.
Article
Nanoscience & Nanotechnology
K. Loeto, G. Kusch, M. Coulon, S. M. Fairdough, E. Le Boulbar, I Girgel, Pa Shields, R. A. Oliver
Summary: In this experiment, InGaN/GaN core-shell nanorods were fabricated to investigate the decrease in radiative efficiency, revealing that the dark ring originates from an agglomeration of point defects at the regrowth interface of GaN. These point defects limit the radiative recombination rate, reducing the radiative efficiency close to the regrowth interface.