Abstract: A theoretical model describing mechanisms of heat transfer in meso-porous silicon (meso-PS) layer based on the effective medium theory is brought forward.The influencing factors of effective thermal conductivity (ETC) of meso-PS,including the porosity of meso-PS,the heat capacity of silicon at constant volume,and the phonon mean free path of silicon,were analyzed theoretically,and a calculation formula of TC of meso-PS was given.The porosities of meso-PS samples prepared by the double-tank electrochemical corrosion method were 62% and 79%, respectively.Their TC values yielded by micro-Raman spectroscopy were 8.315 and 0.949W/(m·K),respectively.Scanning electron microscopy shows that the average characteristic sizes of meso-PS samples with porosities of 62% and 79% are 10 and 5nm,respectively.According to the formula for TC of meso-PS,the theoretical ETC value of a meso-PS layer with a porosity of 62% and an average characteristic size of 10nm is 10.753 W/(m·K),and that of meso-PS layer with a porosity of 79% and an average characteristic size of 5nm is 1.035W/(m·K).It is shown that the theoretical values are quite in good agreement with experimental data.Meso-PS with low TC is well suited for thermal insulation material,which is attractive for use in microsensors and microelectro-mechanical systems.

Key words: :theoretical model, meso-porous silicon, micro-Raman spectroscopy, effective thermal conductivity, microsensors, microelectro-mechanical system