Mustansiriyah Journal of Pure and Applied Sciences

Structural and optical properties of black silicon prepared by wet chemical etching

Abdullah S. Abdulhameed

Mustansiriyah University

Hasan A. Hadi

Raid A. Ismail

DOI: https://doi.org/10.47831/mjpas.v3i1.199

Keywords: Wet Etching, Black silicon, Photoluminescence properties, Surface morphology, energy gap

---

Abstract

The study focuses on the optimization of black silicon fabrication via etching using a solution composed of KOH, NaOH, and Na₂SiO₃ at constant concentrations and varying durations. Surface morphology was analyzed using Field Emission Scanning Electron Microscopy (FE-SEM). The results showed that pyramidal structures were formed on the silicon surface with heights between 1.2 and 4.1 μm. The uniform distribution was confirmed by AFM images. The surface roughness decreased as the etching time increased; it was measured at 14.03 nm for 15 minutes and 5.59 nm for 30 minutes. The properties of photoluminescence (PL) were evaluated using a spectrometer and it was found that peak emission shifts to lower energies (red shift) when etching time is increased. Optical reflectivity decreases sharply when etching time is increased. Additionally, the longer the etching duration, the greater the energy gap of the material which increased from 1.25 eV to approximately 1.4 eV.