Open AccessInvestigation on surface morphological and optical properties of black silicon fabricated by metal-assisted chemical etching with different etchant concentrations
Author(s) -
Nur Afidah Md. Noor,
Mohd Zamir Pakhuruddin
Publication year - 2019
Publication title -
iop conference series. earth and environmental science
Language(s) - English
Resource type - Journals
eISSN - 1755-1307
pISSN - 1755-1315
DOI - 10.1088/1755-1315/268/1/012064
Subject(s) - wafer , materials science , black silicon , silicon , isotropic etching , etching (microfabrication) , optoelectronics , annealing (glass) , reactive ion etching , dry etching , analytical chemistry (journal) , wavelength , optics , nanotechnology , composite material , chemistry , layer (electronics) , physics , chromatography
In this study, the surface morphological and optical properties of black silicon (b-Si) fabricated by two-step metal-assisted chemical etching (MACE) process are investigated. The two-step MACE combines low-temperature annealing of silver (Ag) thin film to produce Ag nanoparticles (NPs) and short etching duration of crystalline silicon (c-Si) wafer. The etching is carried out in HF:H 2 O 2 :DI H 2 O solution for 70 s with different etchant concentrations (represented in the form of volume ratio). The MACE process produces b-Si nanopores on the wafer. Compared with planar c-Si reference, broadband reflection (in 300-1100 nm wavelength region) of the b-Si is significantly lower. B-Si wafer with volume ratio of 1:5:10 exhibits the lowest broadband reflection of 3% at wavelength of 600 nm, which is believed to be due to refractive index grading which leads to enhanced light coupling into the b-Si wafer. The best b-Si wafer (with lowest reflection) shows 50 nm average pillar width and 300 nm height. The increased broadband light absorption results in the highest maximum potential short-circuit current density (J sc(max) ) of 40.9 mA/cm 2 . This represents 55.4% enhancement, if compared with the planar c-Si reference wafer, assuming unity carrier collection.