A Theoretical Study on the Properties of Submicron b-Si Nanostructures for Improved Absorption in b-Si Thermophotovoltaic Cells

Black silicon (b-Si) is a nanostructured surface modification with excellent optical properties and is an attractive candidate for optoelectronic applications. In this work, a preliminary simulation study is done to determine the optical properties of b-Si layers on silicon photovoltaic cells for thermophotovoltaic applications. Finite-difference time-domain method was used to simulate the optical responses of b-Si photovoltaic cells. Black silicon nanostructures of about 50 to 650 nm in diameter and 200 to 1800 nm in height were studied. The optical properties improved with decreasing nanostructure diameter and increasing height. The light trapping properties in these nanostructures were discussed and were attributed to the refractive index gradients of the b-Si layer.