Roman Anufriev

Roman Anufriev
The University of Tokyo | Todai · Institute of Industrial Science

Ph.D.

About

55
Publications
21,116
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
1,202
Citations
Additional affiliations
April 2021 - present
The University of Tokyo
Position
  • Professor (Associate)
October 2019 - April 2020
The University of Tokyo
Position
  • Research Associate
September 2014 - October 2019
The University of Tokyo
Position
  • PostDoc Position
Education
September 2008 - August 2010
Saint Petersburg Academic University
Field of study
  • Electronics and microelectronics
September 2004 - August 2008

Publications

Publications (55)
Article
Full-text available
Future of silicon-based microelectronics depends on solving the heat dissipation problem. A solution may lie in a nanoscale phenomenon known as ballistic heat conduction, which implies conduction of heat without heating the conductor. However, attempts to demonstrate this phenomenon experimentally are controversial and scarce, whereas its mechanism...
Article
Full-text available
Knowledge of the phonon mean free path (MFP) holds the key to understanding the thermal properties of materials and nanostructures. Although several experiments measured the phonon MFP in bulk silicon, MFP spectra in thin membranes have not been directly measured experimentally yet. In this work, we experimentally probe the phonon MFP spectra in su...
Article
Full-text available
Manipulation of thermal fluxes is essential in today’s science and technology. However, modern thermal phononics relies on the wave interference of phonons and thus is truly efficient either at sub-kelvin temperatures or atomic scales. We propose an alternative concept of heat manipulation based on the particle picture of phonons and their ballisti...
Article
Full-text available
Silicon carbide (SiC) aims to be the number one material for power microelectronics due to its remarkable thermal properties. Recent progress in SiC technology finally enabled the fabrication of crystalline SiC nanostructures. Yet, the thermal properties of SiC at the nanoscale remain overlooked. Here, we systematically study heat conduction in SiC...
Article
Full-text available
Efficient heat dissipation in micro/nanoelectronics requires long-distance propagation of heat carriers operated above room temperature. However, thermal phonons—the primary heat carriers in dielectric nanomaterials—dissipate the thermal energy after just a few hundred nanometers. Theory predicts that the mean free path of surface phonon-polaritons...
Article
Full-text available
The existence of a net heat current of conductive thermal waves is demonstrated even in the absence of a mean temperature gradient. This effect, which we called heat shuttling, is generated by the temperature-dependent thermal conductivity of materials excited with a thermal excitation periodically modulated in time. We show that this modulation gi...
Chapter
Thermal management is essential for efficient semiconductor-based quantum systems. In this chapter, we discuss fundamental principles of heat conduction engineering via wave properties of phonons and review recent advances in this field. In phononic crystals—acoustic analogs of photonic crystals—phonons that remain coherent upon scattering on perio...
Article
Full-text available
Thermal transport at the nanoscale level is attracting attention not only because of its physically interesting features such as the peculiar behavior of phonons due to their pronounced ballistic and wave-like properties but also because of its potential applications in alleviating heat dissipation problems in electronic and optical devices and the...
Article
Full-text available
Ballistic thermal transport is a remarkable nanoscale phenomenon with possible applications in microelectronics. In the past decade, research on ballistic thermal transport focused on the measurements of length-dependent thermal conductivity in semiconductor nanowires. In this Perspective article, we review the experimental demonstrations of this p...
Preprint
Full-text available
Long-distance propagation of heat carriers is essential for efficient heat dissipation in microelectronics. However, in dielectric nanomaterials, the primary heat carriers - phonons - can propagate ballistically only for hundreds of nanometres, which limits their heat conduction efficiency. Theory predicts that surface phonon-polaritons (SPhPs) can...
Article
Full-text available
Phononic crystals are the acoustic analogs of photonic crystals and aim at manipulating phonon transport using phonon interference in periodic structures. While such periodic structures are typically two-dimensional, many applications require one-dimensional (1D) wire-like or bulk structures instead. In this Research Update, we summarize the past d...
Article
Full-text available
Guest Editorial article for the special issue of the Journal of Applied Physics called "Photothermics". In this article we cover recent advances in the studies of photoacoustic and photothermal phenomena covered in this special issue.
Article
Full-text available
Improving heat dissipation in increasingly miniature microelectronic devices is a serious challenge, as the thermal conduction in nanostructures is markedly reduced by increasingly frequent scattering of phonons on the surface. However, the surface could become an additional heat dissipation channel if phonons couple with photons forming hybrid sur...
Article
Full-text available
Heat conduction in superlattices demonstrates various atomic-scale effects, one of which is the ultra-low thermal conductivity. Remarkably, theoretical works even promise sub-amorphous thermal conductivity in superlattices made of amorphous materials. Yet, these predictions were not tested experimentally. Here, we experimentally study the cross-pla...
Article
Full-text available
Surface phonon-polaritons (SPhPs) are evanescent electromagnetic waves that can propagate distances orders of magnitude longer than the typical mean free paths of phonons and electrons. Therefore, they are expected to be powerful heat carriers capable of significantly enhancing the in-plane thermal conductance of polar nanostructures. In this work,...
Article
Full-text available
Nanostructuring is the dominant approach for effective thermal conduction control in nanomaterials. In the past decade, researchers have been interested in thermal conduction control by the coherent effects in phononic crystal (PnC) systems. Recent theoretical works predicted that nanopillars on the surface of silicon membranes could cause a dramat...
Article
Full-text available
Ballistic heat conduction remains a controversial nanoscale phenomenon because of its occurrence and strength depending on the material, alloy composition, and temperature. Here, we discuss the impact of ballistic thermal conduction and compare the results with theoretical predictions. We experimentally investigate ballistic thermal transport in Si...
Article
Full-text available
Modern thermoelectric devices incline toward inexpensive, environmentally friendly, and CMOS-compatible materials, such as silicon. To improve the thermoelectric performance of silicon, researchers try to decrease its thermal conductivity using various nanostructuring methods. However, most of these methods have limited efficiency because they are...
Preprint
Full-text available
Surface phonon-polaritons can carry energy on the surface of dielectric films and thus expected to contribute to heat conduction. However, the contribution of surface phonon-polaritons (SPhPs) to thermal transport has not been experimentally demonstrated yet. In this work, we experimentally measure the effective in-plane thermal conductivity of amo...
Article
Full-text available
Ballistic heat conduction in semiconductors is a remarkable but controversial nanoscale phenomenon, which implies that nanostructures can conduct thermal energy without dissipation. Here, we experimentally probed ballistic thermal transport at distances of 400–800 nm and temperatures of 4–250 K. Measuring thermal properties of straight and serpenti...
Article
Full-text available
We propose a simple, low-cost, and large-area method to increase the thermoelectric figure of merit (ZT) in silicon membranes by the deposition of an ultrathin aluminum layer. Transmission electron microscopy showed that short deposition of aluminum on a silicon substrate covers the surface with an ultrathin amorphous film, which, according to rece...
Article
Full-text available
Artificial periodic nanostructures, known as phononic crystals, promise to control the thermal properties of nanostructures in the coherent regime, which can be achieved in semiconductors at low temperatures. Here, we study coherent thermal conduction in silicon nanowires with added periodic wings at sub-Kelvin temperature. Our simulations show tha...
Article
Full-text available
We measure the thermal conductivity of silicon phononic crystals with asymmetric holes at room and liquid helium temperatures and study the effect of thermal rectification, phonon boundary scattering, neck transmission, and hole positioning. Also, we compare the influence of asymmetric holes on thermal conductivity reduction with the one of convent...
Article
Full-text available
Phononic crystals have been studied for the past decades as a tool to control the propagation of acoustic and mechanical waves. Recently, researchers proposed that nanosized phononic crystals can also control heat conduction and improve the thermoelectric efficiency of silicon by phonon dispersion engineering. In this review, we focus on recent the...
Preprint
Full-text available
Future of silicon-based microelectronics relies on solving the heat dissipation problem. A solution may lie in a nanoscale phenomenon known as ballistic heat conduction, which implies heat conduction without heating the conductor. But, attempts to demonstrate this phenomenon experimentally are controversial and scarce whereas its mechanism in confi...
Conference Paper
Full-text available
Use of thermoelectric devices in modern technology is limited by the lack of inexpensive materials with high electrical but low thermal conductivity. Recent studies demonstrated that arrays of holes could reduce the thermal conductivity of thin silicon membranes, while keeping high electrical conductivity. Here, we use micro-TDTR experiments and Mo...
Article
Phonon engineering is expected to contribute to further development of various fields and technologies such as electronics, photonics, thermal engineering, and materials science. Although phonons inherently exist in condensed matter, their behavior strongly depends on the scale of the system and the materials, and they play a major role in electric...
Article
Full-text available
Semiconductor nanowires are potential building blocks for future thermoelectrics because of their low thermal conductivity. Recent theoretical works suggest that thermal conductivity of nanowires can be further reduced by additional constrictions, pillars or wings. Here, we experimentally study heat conduction in silicon nanowires with periodic win...
Article
Full-text available
In search of efficient thermoelectric nanostructures, many theoretical works predicted that nanopillars, placed on the surface of silicon membranes, nanobeams or nanowires, can reduce the thermal conductivity of these nanostructures. To verify these predictions, we experimentally investigate heat conduction in suspended silicon nanobeams with array...
Article
Full-text available
The world communicates to our senses of vision, hearing, and touch in the language of waves, because light, sound, and even heat essentially consist of microscopic vibrations of different media. The wave nature of light and sound has been extensively investigated over the past century and is now widely used in modern technology. However, the wave n...
Article
The in-plane thermal conductivity of silicon phononic membranes is investigated by micro time domain thermoreflectance and Monte Carlo simulations. Strong reduction of thermal conductivity is observed mainly due to phonon boundary scattering for both aligned and staggered lattices of holes. The measured and calculated thermal conductivities of the...
Article
Full-text available
Unlike classical heat diffusion at macroscale, nanoscale heat conduction can occur without energy dissipation because phonons can ballistically travel in straight lines for hundreds of nanometres. Nevertheless, despite recent experimental evidence of such ballistic phonon transport, control over its directionality, and thus its practical use, remai...
Data
Supplementary Figures, Supplementary Notes and Supplementary References
Article
Full-text available
Pillar-based phononic crystals belong to a class of acoustic metamaterials that can control heat conduction based on the design of the structure. In this work, we systematically investigate how various parameters of pillar-based phononic crystals affect thermal conductance at low temperatures. We find that the lowest thermal conductance is achieved...
Article
Full-text available
We present experimental and theoretical investigations on the roles of the limiting dimensions, such as the smallest dimension, surface roughness, and density of holes in the reduction of thermal conductivity of one-dimensional phononic nanostructures at temperatures of 4 and 295 K. We dis- cover that the thermal conductivity does not strongly depe...
Article
Full-text available
We have experimentally investigated the impact of dimensions and temperature on the thermal conductivity of silicon nanowires fabricated using a top-down approach. Both the width and temperature dependences of thermal conductivity agree with those in the existing literature. The length dependence of thermal conductivity exhibits a transition from s...
Article
Full-text available
We investigate the impact of various phonon scattering mechanisms on the in-plane thermal conductivity of suspended silicon thin films with two-dimensional periodic arrays of holes, i.e., phononic crystal (PnC) nanostructures. A large amount of data on the PnC structures with square, hexagonal, and honeycomb lattices reveals that the thermal conduc...
Article
Full-text available
The impact of lattice type, period, porosity and thickness of two-dimensional silicon phononic crystals on the reduction of thermal conductance by coherent modification of phonon dispersion is investigated using the theory of elasticity and finite element method. Increase in the period and porosity of the phononic crystal affects the group velocity...
Article
Full-text available
The emission polarization of single InAs/InP quantum dot (QD) and quantum rod (QR) nanowires is investigated at room temperature. Whereas the emission of the QRs is mainly polarized parallel to the nanowire axis, the opposite behavior is observed for the QDs. These optical properties can be explained by a combination of dielectric effects related t...
Preprint
Phonons, quanta of lattice vibrations in condensed matter, are the main heat carriers in nonmetals promoting both particle and wave effects in transport properties, similar to that of photons. Numerous studies have so far reported large reductions of the thermal conductivity by enhancing incoherent scattering, which is essentially relevant to the p...
Article
Full-text available
A theoretical study of coherent phonon scattering in thin-film phononic-crystal nanostructures (also called thermocrystals) is presented. It is commonly assumed that phononic crystals may only reduce thermal conductivity of materials. In this theoretical paper, contrary to this assumption, we demonstrate that phononic nanopatterning can enhance the...
Article
Full-text available
In-plane thermal conduction and phonon transport in both single-crystalline and polycrystalline Si two-dimensional phononic crystal (PnC) nanostructures were investigated at room temperature. The impact of phononic patterning on thermal conductivity was larger in polycrystalline Si PnCs than in single-crystalline Si PnCs. The difference in the impa...
Article
Full-text available
We report on the evidence of a strain-induced piezoelectric field in wurtzite InAs/InP quantum rod nanowires. This electric field, caused by the lattice mismatch between InAs and InP, results in the quantum confined Stark effect and, as a consequence, affects the optical properties of the nanowire heterostructure. It is shown that the piezoelectric...
Conference Paper
Full-text available
Purely wurtzite InAs/InP quantum rod nanowires (QRod-NWs) emitting at 1.55 μm have been successfully grown on silicon substrates by VLS assisted molecular beam epitaxy. Microphotoluminescence studies of single QRod-NWs reveal a highly linearly polarized emission parallel to the nanowires axis. This very high degree of linear polarization (> 0.9) ca...
Thesis
Full-text available
This thesis is focused upon the experimental investigation of optical properties of InAs/InP nanowire heterostructures by means of photoluminescence (PL) spectroscopy. First, it was demonstrated that the host-substrate may have significant impacts on the optical properties of pure InP nanowires, as due to the strain, created by the difference in th...
Article
Full-text available
Photoluminescence (PL) quantum efficiency (QE) is experimentally investigated, using an integrating sphere, as a function of excitation power on both InAs/InP quantum rod nanowires (QRod-NWs) and radial quantum well nanowires (QWell-NWs) grown on silicon substrates. The measured values of the QE are compared with those of the planar analogues such...
Article
Full-text available
The absorption and emission polarization properties of InAs quantum rods embedded in InP nanowires (NWs) are investigated by mean of (micro-)photoluminescence spectroscopy. It is shown that the degree of linear polarization of emission (0.94) and absorption (0.5) of a single NW can be explained by the photonic nature of the NW structure. Knowing th...
Article
Full-text available
It is shown that cylindrical Bragg reflector structures with either a metal core, a metal cladding, or both can support Tamm plasmon polaritons (TPPs) that can propagate axially along the interface between the metallic layer and the adjacent dielectric. A transfer matrix formalism for cylindrical multilayered structures is used in association with...
Article
Full-text available
Wurtzite InP nanowires (NWs), transferred onto various substrates, were investigated by low temperature micro-photoluminescence. A clear PL emission shift, depending on the substrate, is observed and attributed to the substrate-induced strain, generated due to the difference in the thermal expansion coefficients of the InP NWs and the host-substrat...
Article
Full-text available
InP nanowires grown on silicon substrate are investigated using time-resolved spectroscopy. A strong modification of the exciton lifetime is observed (from 0.11 to 1.2 ns) when the growth temperature is increased from 340 °C to 460 °C. This strong dependence is not related to the density of zinc-blende insertions in the wurtzite nanowires or to the...
Article
Full-text available
Optical properties of wurtzite InP/InAs/InP core-shell nanowires grown on silicon substrates by solid source molecular beam epitaxy are studied by means of photoluminescence and microphotoluminescence. The growth conditions were optimized to obtain purely wurtzite radial quantum wells emitting in the telecom bands with a radiative lifetime in the 5...

Network

Cited By

Projects

Projects (2)
Project
We investigate nanoscale heat conduction in quasi-ballistic regime in nanowires, membranes, and phononic structures at temperatures in 4 - 300 K range. We aim to find materials, geometrical structures, and length-scales that allow ballistic heat conduction at room temperature.
Project
We study heat conduction in pillars-based phononic crystals. We aim to experimentally test theoretical predictions of the thermal conductivity reduction caused by local resonances in pillars and study both coherent and incoherent types of phonon scattering caused by the pillars.