Effect of Porosity on Thermal Properties of Porous Silicon

We report on the thermal properties of nanostructured silicon prepared by using a laser-assisted electrochemical route. The main thermal properties of porous silicon were directly measured utilizing the non-destructive approach of C-Therm TCi.™. To investigate how the porosity affects the thermal properties of porous silicon layers, variation of the etching time was a primary parameter in this work. Scanning electron microscope (SEM) images showed that the formation of the surface of the mud-like porous silicon structure and the porosity ranged from 38% to 62% depending on etching times. Practically, the porous silicon layer porosity and thickness increase as the etching time increases. The X-ray diffraction studies confirm that the crystallite size of the nanocrystalline porous silicon decreases and the peaks are widened when the etching time and porosity are increased. The values of thermal conductivity, thermal effusivity, and thermal diffusivity of porous silicon with a porosity of 62% were 0.55 W m−1.k−1, 926.8 W m-2 k−1, and 0.35 mm−2.s−1, respectively.