Heat transport at nanoscales in semiconductors is investigated with a statistical method. The Boltzmann equation (BTE), which characterizes phonon motion and interaction within the crystal lattice, has been simulated Monte Carlo technique. Our model takes into account media frequency properties through dispersion curves for longitudinal transverse acoustic branches. BTE collisional term involving scattering processes relaxation times approximation theory. A new distribution function...

The authors study the thermal conductivity of silicon nanowires by simulation phonon motion and interactions through a dedicated Monte Carlo model. This model solves Boltzmann transport equation, taking into account acoustic mode dispersion curves three (the normal umklapp processes). confinement, which limits in such structures, is described diffuse reflection at lateral boundaries nanowire without any adjustment boundary collision time, depends on specularity factor. They compare results...

Heat conduction of nanoporous silicon and germanium thin films is studied thanks to a statistical approach. Resolution phonon Boltzmann transport equation performed with Monte Carlo technique in order assess thermal conductivity. Sensitivity this latter property respect parameters such as mean free path characteristics the pores (distribution, size, porosity) discussed compared predictions from analytical models. Results point out that properties might be tailored through design porosity...

A spectroscopic study of a laser-induced plume created during the welding stainless steel and other materials (iron chromium) has been carried out. pulsed Nd:YAG laser 1000 W average power is used. The evolutions electron temperature density have studied for several parameters. We use working powers from 300 to 900 pulse durations between 1.5 5 ms. influence shielding gases like nitrogen argon taken into account. Temperature calculations are based on observation relative intensities shapes...

Thermal transport properties of crystalline/amorphous silicon superlattices using molecular dynamics are investigated. We show that the cross-plane conductivity is very low and close to bulk amorphous even for layers as thin ≃ 6 Å. The thermal weakly increases with temperature which associated a decrease Kapitza resistance at interface. This property further investigated considering spatial analysis phonon density states in domains Interestingly, shown display large anisotropy, according...

Germanium manganese compounds exhibit a variety of stable and metastable phases with different stoichiometry. These materials entail interesting electronic, magnetic thermal properties both in their bulk form as heterostructures. Here we develop validate transferable machine learning potential, based on the high-dimensional neural network formalism, to enable study Mn$_x$Ge$_y$ over wide range compositions. We show that potential fitted minimal training set reproduces successfully structural...

In this paper we present a systematic and well controlled procedure for building atomistic amorphous/crystalline interfaces in silicon, dedicated to the molecular dynamics simulations of superlattices core/shell nanowires. The obtained structures depend on technique used generate amorphous phase their overall quality is estimated through comparisons with structural information interfacial energies available from experimental theoretical results. While most related studies focus single planar...

The thermal conductivities of nanoporous and nanocomposite silicon with incorporated amorphous phases have been computed by molecular dynamics simulations. A systematic investigation the porosity width shell contouring a spherical pore has made. impact phase nanoinclusions in crystalline matrix also studied same fraction as to achieve comparison. key parameter for all configurations or without is proved be interface (between void) volume ratio. We obtain sub-amorphous conductivity several...

The in-plane thermal conductivity of silicon phononic membranes is investigated by micro time domain thermoreflectance and Monte Carlo simulations. Strong reduction observed mainly due to phonon boundary scattering for both aligned staggered lattices holes. measured calculated conductivities the porous with cylindrical holes are found be in good quantitative agreement (at 4 K 300 K). A significant difference between lattice identical porosities observed. This shown arise from ballistic...

We report on thermal transport properties of wurtzite GaN in the presence dislocations, by using molecular dynamics simulations. A variety isolated dislocations a nanowire configuration were analyzed and found to reduce considerably conductivity while impacting its temperature dependence different manner. demonstrate that screw factor two, influence edge is less pronounced. The relative reduction correlated with strain energy each five studied types nature bonds around dislocation core....

Nano-engineering crystalline materials can be used to tailor their thermal properties. By adding new nanoscale phonon scattering centers and controlling size, one effectively decrease the mean free path, hence conductivity of a fully material. In this Letter, we use 3ω method in temperature range 100–300 K experimentally report on more than threefold reduction an epitaxially grown germanium thin film with embedded polydispersed Ge3Mn5 nano-inclusions diameters ranging from 5 25 nm. A...

In this study, we conducted calculations to determine the thermal conductivity of silicon nanowires with various shapes and cross-sectional designs using Monte Carlo method combined Green–Kubo heat flow autocorrelation. This computational approach is known for its reliability in predicting properties complex nanostructured devices. We specifically examined circular or rectangular sections serpentine fishbone modulations. Our findings indicate that nanowire's geometry significantly impacts...

The wetting characteristics of fluids play a crucial role in various fields interface and surface science. Contact angle serves as fundamental indicator behavior. However, accurate quantification phenomena even at the macroscale often poses challenges, particularly due to hysteresis between receding advancing contact angles. complexity increases further nanoscale, where significant volume interphase region causes ambiguity defining "dividing surface." In this study, we use molecular dynamics...

The thermal conductivity of a series structural, diameter, and core/shell modulated silicon nanowires is computed by molecular dynamics simulations using the nonequilibrium method. purpose this study to appraise impact surface roughness, amorphous parts integration, diameter modulation on reduction. addition both regions nanoconstrictions allows us reach close that pristine nanowires, while preserving certain degree crystallinity. This could result in interesting properties for...

Abstract This paper investigates thermal transport in a nanocomposite system consisting of porous silicon matrix filled with ionic liquid. Firstly, the conductivity and heat capacity two imidazolium one ammonium liquids were evaluated using photoacoustic approach piezoelectric configuration differential scanning calorimetry, respectively. Then, properties composite "ionic liquid confined inside matrix" investigated gas-microphone configuration. The results demonstrated significant...

We study heat transport in semiconductor nanostructures by solving the Boltzmann equation means of discrete ordinate method. Relaxation time and phase group velocity spectral dependencies are taken into account. The Holland model phonon relaxation is revisited recalculated from dispersion relations (taken literature) order to match bulk silicon germanium values. This improved then used predict nanowire nanofilm thermal properties both ballistic mesoscopic regimes.

We report on scaling behavior of the thermal conductivity width-modulated nanowires and nanofilms that have been studied with phonon Monte Carlo technique. It has found reduction scales nanostructure transmissivity, a property entirely determined by modulation geometry, irrespectively material choice. Tuning is possible width-modulation without strict limitations for profile. In addition, very significant constriction resistance due to width-discontinuity identified, in analogy contact...

Thermal conductivity value of sponge-like meso-porous germanium (meso-PGe) layers measured by means photoacoustic technique is reported. The room temperature thermal found to be equal 0.6 W/(m K). experimental results are in excellent agreement with molecular dynamic and Monte Carlo simulations. Both experiments simulations show an important reduction the meso-PGe compared bulk Ge. obtained reveal as interesting candidate for both thermoelectric photovoltaic applications which transport a...