Enhanced terahertz emission and Raman signal from silicon nanopyramids

• Main Authors: Felix, Mark Jayson, Muldera, Joselito E., Somintac, Armando S., Salvador, Arnel A., Estacio, Elmer S.
• Format: text
• Published: Animo Repository 2015
• Subjects: Nanosilicon; Raman spectroscopy; Terahertz spectroscopy; Physics
• Online Access: https://animorepository.dlsu.edu.ph/faculty_research/8134
• Institution: De La Salle University

The Raman scattering and Terahertz emission of silicon nanopyramids (SiNPys) formed at different etching times were investigated. Additionally, photoluminescence spectroscopy measurements were performed to investigate the recombination properties of SiNPys. The SiNPys were fabricated via wet chemical etching of heavily doped p-type silicon (100) in potassium hydroxide (KOH) solution. The formation of nanopyramidal structures was verified using Scanning Electron Microscopy (SEM). Enhanced Raman and THz signals were observed from SiNPys compared to un etched silicon surface. The enhancement of Raman signal in SiNPys is ascribed to the enhanced photon absorption from efficient light trapping effect of the nanopyramids. Moreover, broadening of the Raman peaks was observed indicating an amorphous-like structure with prolonged etching. The enhancement of THz signal in SiNPys is ascribed to increased transient current on the nanopyramids' surface. The maximum enhancement for Raman and THz signals was found for SiNPys formed after 30 mins etching. Further etching beyond 30 mins resulted in weaker Raman and THz signals. Results suggest strong correlation between the THz emission and Raman scattering of SiNPy's. This correlation may be understood from the vibrational mode dependence of both Raman scattering and THz emission.