Development and Investigation of Thermal Devices on Fully Porous Silicon Substrates

Silicon Porosification: Approaches to PSi Parameters Control

“…This dual transport route model is consistent with the presence of two Meyer-Neldel rules (MNR). The conductivity prefactor σ 0 has been reported by Lubianiker and Balberg (1997) to follow two distinct energy activation regimes, one that is very similar to what is found in amorphous silicon (see Figure 6.16). Urbach et al (2007), using state-of-the-art oxidation of PSi, observed the other route as appearing when the disordered tissue is oxidized, and ascribed it to tunneling and hopping in between the nanocrystals.…”

“…In crystalline semiconductor, the main limitations to the value of μ are acoustic phonon and ionized impurity scattering; in PSi, these mechanisms are also expected to be present, but the very low drift mobility values in comparison to bulk silicon suggest that typical features of PSi, such as the greater surface area, surface chemistry, skeletal structure, or quantum confinement, must play a dominant role. In other words, the different mechanisms Lubianiker Y. andBalberg I., Phys. Rev.…”

Thermal conductivity of highly porous Si in the temperature range 4.2 to 20 K

“…This is attributed to phonon confinement in the Si nanostructures and phonon scattering at porous Si large internal surface. The room temperature thermal conductivity of porous Si was extensively investigated in the literature (see a list in [ 3 ]), and the material is now established as an effective low thermal conductivity substrate for Si-based thermal devices [ 4 ], including flow sensors [ 5 - 8 ], gas sensors [ 9 ], accelerometers [ 10 ], and thermoelectric devices [ 11 , 12 ]. An increasing interest is recently devoted to the potential use of porous Si as a thermoelectric material with high figure of merit (ZT), achievable with its low thermal conductivity, combined with an intentional doping to increase its electrical conductivity [ 13 - 15 ].…”