Effects of annealing temperature towards properties of black silicon fabricated by aluminium-assisted chemical etching

Black silicon (b-Si) is a promising absorber material for photovoltaic (PV) application. This paper studies the effects of annealing temperature towards surface morphological and optical properties of b-Si fabricated by aluminium-assisted chemical etching (AACE) process. In this work, the AACE process is realized by depositing aluminium (Al) thin film with 12 nm thickness on crystalline silicon (c-Si) wafers by direct current (DC) sputtering, followed by annealing the wafers at 250-450 degrees C in nitrogen (N-2) atmosphere. Subsequently, the wafers are etched in a wet chemical solution containing hydrofluoric acid (HF), hydrogen peroxide (H2O2) and deionized (DI) water for 20 min at room temperature. From the findings, annealing the sample at 400 degrees C leads to formation of b-Si nanopores with the deepest nanopores and the highest surface coverage. This temperature also leads to the lowest broadband reflection within 300-1100 nm wavelength region. As a result, the highest average absorption enhancement of 1.61 is achieved when the absorption of the b-Si annealed at 400 degrees C is normalized to the absorption of the planar c-Si reference.

Automated summary

The study examined the impact of annealing temperature on the surface morphology and optical properties of b-Si fabricated using AACE process, finding that annealing at 400 degrees Celsius resulted in the formation of optimal surface features.