Temperature-dependent thermal conductivity of porous silicon

Abstract

The thermal conductivity of electrochemically etched porous silicon (PS) layers was determined over a wide temperature range (T = 35 - 320 K) using the dynamic technique. Both the doping level of the silicon wafers (p and ) and the porosity P of the porous layers (P = 64 - 89%) were varied. The measured thermal conductivities were three to five orders of magnitude smaller than the values for bulk silicon. Furthermore, they increase with increasing the wafer doping level and with decreasing the porosity P of the layers. For all investigated PS layers the thermal conductivity increases with temperature. The results are discussed in terms of a simple model for heat conduction in PS based on the phonon diffusion model.

Size and porosity effects on thermal conductivity of nanoporous material with an extension to nanoporous particles embedded in a host matrix

“…2 Effective thermal conductivity (Wm -1 K -1 ) as a function of porosity for pore radii of 2 (•), 5 (▲), 10 (■) and 100 (♦) nm. Comparison of the results of our model (solid lines) with reported experimental data [1,7] and, in dashed lines, the hydrodynamic model [8] (Fig. 2a) and the Lysenko model [23] (Fig.…”

“…It is confirmed that the results provided by the Eucken, Sumirat and percolation models are rather far from the experimental data for all the ranges considered. A further comparison between EIT, the hydrodynamic model and experimental data [1,7,23] for several values of the pore radii ( = 2, 5, 10 and 100 nm) is found in Fig. 2(a).…”

“…2(b), but instead of the hydrodynamic model, we compare with the Lysenko model. [1,7] and, in dashed lines, the hydrodynamic model [8] (Fig. 2a) and the Lysenko model [23] (Fig.…”

“…It has therefore fostered an increasing interest during the last decade. Thermal properties of nanoporous media are generally investigated by referring to, for instance, kinetic theory of phonons [3], molecular simulations [5], Monte Carlo simulations [6], two-component materials [7] or hydrodynamic models [8]. In this work, we take a different route and prefer a thermodynamic approach.…”

Thermal transport in 2- and 3-dimensional periodic “holey” nanostructures

“…In the same work, the thermal conductivity of as-prepared meso-porous silicon (45% porosity) was measured to be 80 W/m K which dropped to 2.7 W/m K upon oxidation at 300 • C. Temperature dependent measurements in the range of 35 K-320 K using the 3ω method were first reported by Gesele et al 57 The thermal conductivities of all the investigated samples increased with increasing temperature, and were less than 1W/ m K at room temperature. A minimum value of 0.03 W/m K was reported for p-type porous silicon with 89% porosity and 4.5±0.6 nm crystallite size.…”