Study of black silicon obtained by cryogenic plasma etching : Approach to achieve the hot spot of a thermoelectric energy harvester

Abstract : n this paper, we study the enhanced absorption properties of micro/nano structured silicon surface under incident electromagnetic illumination and its capacity to convert light into heat. We simulate the optical reflectance of three-dimensional micro/nano silicon cones of different dimensions and under different electric field incident angles. According to the favorable simulation results, we fabri- cate black silicon with conical microstructures that exhibits excellent anti-reflectivity behavior. Plasma etching under cryogenic temperatures is used for this purpose in an induc- tively coupled plasma-reactive ion etching reactor. The reflectance of the black silicon is measured to be approxi- mately 1 % in the optical wavelength range, by using an integrating sphere coupled to a calibrated spectrometer. Fur- thermore, a device integrating a resistance temperature detector in a black silicon area is developed in order to investigate its efficiency as a photo-thermal converter