Reflectance characteristics of silicon surface fabricated with the arrays of uniform inverted pyramid microstructures in UV-visible range

• Main Authors: Abdullah, Mohd. Faizol, Hashim, Abdul Manaf
• Format: Article
• Language: English
• Published: Penerbit UKM 2019
• Subjects: TA Engineering (General). Civil engineering (General)
• Online Access: http://eprints.utm.my/id/eprint/89260/1/MohdFaizolAbdullah2019_ReflectanceCharacteristicsofSiliconSurfaceFabricated.pdf; http://eprints.utm.my/id/eprint/89260/; http://dx.doi.org/10.17576/jsm-2019-4806-02
• Institution: Universiti Teknologi Malaysia

In this paper, inverted pyramidal microstructures are designed and fabricated on silicon (Si) surface. The characteristics of surface reflectance are simulated using two-dimensional (2D) finite-difference time-domain (FDTD) method by varying the spacing (S) and width (W) of the pyramidal microstructures. The results showed that the effect of S is more significant compared to W where the reflectance of the irradiated light has been increased gradually with the increase of S from 0 to 3 µm, and the difference is around 9.6%. Due to the etching constraint, S= 3 µm is chosen for the fabrication. Textured structure is fabricated by the anisotropic etching of tetramethyl-ammonium hydroxide (TMAH) with additional of isopropyl alcohol (IPA). Long etching time of 120 min is required to form uniform arrays of pyramidal microstructures with smooth and well-terminated four sidewalls at (111) plane. Due to the undercut etching under SiO2 mask, it results to the formation of slightly larger W and smaller S in the fabricated structures. The measured average reflectance in UV-visible range for the Si with inverted pyramidal microstructures is very low down to 10.4%. The discrepancy between the measured and simulated values is speculated to be due to the use of 2D FDTD instead of three-dimensional (3D) FDTD.