Optimization of etching time for broadband absorption enhancement in black silicon fabricated by one-step electroless silver-assisted wet chemical etching

We report optimization of etching time for enhanced broadband light absorption in black silicon (b-Si) fabricated by one-step electroless silver-assisted wet chemical etching in aqueous solution of HF:AgNO3. Surface morphological characterization confirms presence of b-Si nanowires with heights of 2.0-2.9 mu m with an average diameter of about 100 nm. The b-Si nanowires show excellent suppression of weighted average reflectance (WAR) in the 300-1100 nm wavelength region. After 80 s etching, b-Si nanowires with height of 2.9 mu m lead to WAR of 6%. This results in absorption of 94% at wavelength of 600 nm. The enhanced broadband light absorption results in a maximum potential short-circuit current density (J(sc(max))) of up to 39.2 mA/cm(2), or 49% enhancement compared to c-Si reference. The optimized broadband absorption is crucial to realize high-efficiency c-Si solar cells.