Thermally‐Active Screw Dislocations in Si Nanowires and Nanotubes

Abstract

Dislocations significantly influence the physical properties of nanomaterials. Nonequilibrium molecular dynamics simulations uncover significant reductions in thermal conductivity when <110> Si nanowires contain axial screw dislocations. The effect can act in combination with other known thermal conductivity limiting mechanisms, and thus can enable the further optimization of the figure of merit for a new family of complex thermoelectric nanomaterials.

Nanophononics: state of the art and perspectives

“…Complementary to MD, the Landauer approach [35] with phonon Green's function (GF) is also widely used in thermal transport calculations [36][37][38][39][40]. GF was developed originally for the calculation of electron transport [41] and it has been only recently applied to phonon transport [36,37].…”

Blocking Phonon Transport by Structural Resonances in Alloy-Based Nanophononic Metamaterials Leads to Ultralow Thermal Conductivity

“…The ability of manipulating such low frequencies with small branches is the key advantage of the resonant mechanism over the scattering mechanism, where the size of scattering sources has to be larger than or comparable to the phonon wavelength. Generally, the phonon scattering mechanism provides an e cient way to block the high frequency phonons while it remains challenging in dealing with phonons with, for example, f 6 2 THz in Si NWs [44] and carbon nanotubes [45]. In contrast with scattering strategies, where the scattering source is located inside the material, the resonant mechanism applies the wave nature of phonons and is produced from a position outside from the main structure.…”

Native surface oxide turns alloyed silicon membranes into nanophononic metamaterials with ultralow thermal conductivity

“…Significant efforts have been made to understand and engineer heat transport in nanoscale silicon due to its natural abundance and technological relevance [9][10][11][12]. In the past decade researchers explored strategies to obtain silicon based materials with low thermal conductivity (TC) and unaltered electronic transport coefficients, so to achieve high thermoelectric figure of merit and enable silicon-based thermoelectric technology [11][12][13][14][15][16][17][18].From the earlier studies it was recognized that lowdimensional silicon nanostructures, such as nanowires, thin films and nano membranes feature a largely reduced TC, up to 50 times lower than that of bulk at room temperature. TC reduction becomes more prominent with the reduction of the characteristic dimension of the nanostructures [19][20][21][22].…”