Crystal orientation dependence of alternating current photo-assisted (ACPEC) porous silicon for potential optoelectronic application. Issue 1 (11th December 2019) - Abd Rahim, Alhan Farhanah
Abstract : Purpose: Porous silicon (PS) was successfully fabricated using an alternating current photo-assisted electrochemical etching (ACPEC) technique. This study aims to compare the effect of different crystal orientation of Si n (100) and n (111) on the structural and optical characteristics of the PS. Design/methodology/approach: PS was fabricated using ACPEC etching with a current density of J = 10 mA/cm 2 and etching time of 30 min. The PS samples denoted by PS100 and PS111 were etched using HF-based solution under the illumination of an incandescent white light. Findings: FESEM images showed that the porous structure of PS100 was a uniform circular shape with higher density and porosity than PS111 . In addition, the AFM indicated that the surface roughness of porous n (100) was less than porous n (111). Raman spectra of the PS samples showed a stronger peak with FWHM of 4.211 cm −1 and redshift of 1.093 cm −1 . High resolution X-ray diffraction revealed cubic Si phases in the PS samples with tensile strain for porous n (100) and compressive strain for porous n (111). Photoluminescence observation of porous n (100) and porous n (111) displayed significant visible emissions at 651.97 nm (Eg = 190eV) and 640.89 nm (Eg = 1.93 eV) which was because of the nano-structure size of silicon through the quantum confinement effect. The size of Si nanostructures was approximately 8 nm from a quantized state effective mass theory. Originality/value: The work presented crystal orientation dependence of Si n (100) and n (111) for the formation of uniform and denser PS using new ACPEC technique for potential visible optoelectronic application. The ACPEC technique has effectively formed good structural and optical characteristics of PS.