Ultra-thin free-standing single crystalline silicon membranes with strain control

Shchepetov, A.; Prunnila, Mika; Alzina, Francesc; Schneider, Lutz; Cuffe, J.; Jiang, Haochuan; Kauppinen, Esko I.; Torres, C. M. Sotomayor; Ahopelto, Jouni

doi:10.1063/1.4807130

Cited by 60 publications

(51 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The introduction of controlled stress (σ) in the membrane offers an additional degree of freedom to tailor the phonon dispersion relations [61]. A schematic representation of a stressed membrane with a surrounding strain-controlling frame is shown in Figure 2a [62].…”

Section: Confinement Effects In Low-dimensional Structures: Discretismentioning

confidence: 99%

Nanophononics: state of the art and perspectives

et al. 2016

View full text Add to dashboard Cite

Abstract. Understanding and controlling vibrations in condensed matter is emerging as an essential necessity both at fundamental level and for the development of a broad variety of technological applications. Intelligent design of the band structure and transport properties of phonons at the nanoscale and of their interactions with electrons and photons impact the efficiency of nanoelectronic systems and thermoelectric materials, permit the exploration of quantum phenomena with micro-and nanoscale resonators, and provide new tools for spectroscopy and imaging. In this colloquium we assess the state of the art of nanophononics, describing the recent achievements and the open challenges in nanoscale heat transport, coherent phonon generation and exploitation, and in nano-and optomechanics. We also underline the links among the diverse communities involved in the study of nanoscale phonons, pointing out the common goals and opportunities.

show abstract

Section: Confinement Effects In Low-dimensional Structures: Discretismentioning

confidence: 99%

Nanophononics: state of the art and perspectives

et al. 2016

View full text Add to dashboard Cite

show abstract

mentioning

confidence: 99%

“…This discovery opens up the possibility to further optimize the TC of ultra-thin silicon membranes by combining resonances with mass scattering, which affects phonons with higher frequency (ω 4 THz). We show that alloying the crystalline core of ultra-thin membranes with a small percentage of substitutional germanium atoms brings forth ultra-low TC in silicon membranes with technologically viable thickness [33].All TCs are calculated with equilibrium molecular dynamics (EMD) simulations at 300 K using LAMMPS [34] with interatomic interactions described by the widely used Tersoff potential [35][36][37]. The equations of motion are integrated with the velocity Verlet algorithm arXiv:1705.03143v1 [cond-mat.mtrl-sci]…”

mentioning

confidence: 99%

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

et al. 2017

View full text Add to dashboard Cite

A detailed understanding of the relation between microscopic structure and phonon propagation at the nanoscale is essential to design materials with desired phononic and thermal properties. Here we uncover a new mechanism of phonon interaction in surface oxidized membranes, i.e., native oxide layers interact with phonons in ultra-thin silicon membranes through local resonances. The local resonances reduce the low frequency phonon group velocities and shorten their mean free path. This effect opens up a new strategy for ultralow thermal conductivity design as it complements the scattering mechanism which scatters higher frequency modes effectively. The combination of native oxide layer and alloying with germanium in concentration as small as 5% reduces the thermal conductivity of silicon membranes to 100 time lower than the bulk. In addition, the resonance mechanism produced by native oxide surface layers is particularly effective for thermal condutivity reduction even at very low temperatures, at which only low frequency modes are populated.Controlling terahertz vibrations and heat transport in nanostructures has a broad impact on several applications, such as thermal management in micro-and nano-electronics, renewable energies harvesting, sensing, biomedical imaging and information and communication technologies [1][2][3][4][5][6][7][8]. 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]. Theory and experiments consistently show that surface disorder and the presence of disordered material at surfaces play a major role in determining the TC of nanostructures [12,[23][24][25]. However, a comprehensive understanding of the physical mechanisms underlying so large TC reduction is lacking. The effect of surface roughness and surface disorder on phonons has been so far interpreted in terms of phonon scattering [26][27][28][29][30], but scattering would not account for mean free path reduction of long-wavelength low-frequency modes. Recent theoretical work demonstrated that surface nanostructures, such as nanopillars at the surface of thin films or nanowires, can efficiently reduce TC through resonances, a mechanism that is intrinsically different from scattering [31,32]. Surface resonances alter directly phonon dispersion relations by hybridizing with prop...

show abstract

“…The membranes with areas of ∼500 × 500 micrometer squared were fabricated on 150 mm silicon-on-insulator (SOI) wafers using Si MEMS processing techniques [24]. The underlying Si substrate and the buried oxide layer were removed through a combination of dry and wet etching techniques to leave a top layer of suspended silicon.…”

mentioning

confidence: 99%

Reconstructing phonon mean-free-path contributions to thermal conductivity using nanoscale membranes

et al. 2015

View full text Add to dashboard Cite

Knowledge of the mean-free-path distribution of heat-carrying phonons is key to understanding phononmediated thermal transport. We demonstrate that thermal conductivity measurements of thin membranes spanning a wide thickness range can be used to characterize how bulk thermal conductivity is distributed over phonon mean free paths. A noncontact transient thermal grating technique was used to measure the thermal conductivity of suspended Si membranes ranging from 15-1500 nm in thickness. A decrease in the thermal conductivity from 74-13% of the bulk value is observed over this thickness range, which is attributed to diffuse phonon boundary scattering. Due to the well-defined relation between the membrane thickness and phonon mean-free-path suppression, combined with the range and accuracy of the measurements, we can reconstruct the bulk thermal conductivity accumulation vs. phonon mean free path, and compare with theoretical models.

show abstract

Ultra-thin free-standing single crystalline silicon membranes with strain control

Cited by 60 publications

References 25 publications

Nanophononics: state of the art and perspectives

Nanophononics: state of the art and perspectives

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

Reconstructing phonon mean-free-path contributions to thermal conductivity using nanoscale membranes

Contact Info

Product

Resources

About