Study of black silicon obtained by deep reactive ion etching - approach to achieving the hot spot of a thermoelectric energy harvester

In this paper we study the enhanced absorption properties of micro/nano structured silicon surface under incident electromagnetic (EM) illumination and then its capacity to convert light to heat. We then simulate the optical reflectance of the 3D micro/nano silicon cones of different dimensions. Equipped with the favorable simulation results we fabricate black silicon with excellent anti-reflectivity by using deep reactive ion etching (DRIE) under cryogenic temperatures. Reflectance measurement with an integrating sphere is approximately 1% in the optical wavelength range. Following this, black silicon with integrated resistance temperature detector (RTD) is developed to investigate its efficiency of the photo-thermal conversion.