Sains Malaysiana 48(8)(2019): 1745–1752

http://dx.doi.org/10.17576/jsm-2019-4808-21

Novel Surface-Enhanced Raman Scattering Substrate based on Functionalized Silicon Nanowires

(Raman Permukaan-Dipertingkatkan Sebaran Substrat Baru berasaskan Silikon Berfungsi Wayar Nano)

IRAM MAHMOOD¹*, ISHAQ AHMAD^2,3 & ISHFAQ AHMAD⁴

¹Department of Industrial Engineering, College of Engineering, King Khalid University Abha 61413, Kingdom of Saudi Arabia

²National Center for Physics, Islamabad, 44000, Pakistan

³NPU-NCP Joint International Research Center for Advanced Nanomaterials and Defects Engineering, Northwestern Polytechnical University, Xi'an 710072, China

⁴Department of Mathematics and Statistics, Faculty of Basic and Applied Sciences, International Islamic University, Islamabad, Pakistan

Received: 11 February 2019/Accepted: 21 May 2019

ABSTRACT

This study reports synthesis of a new Surface-Enhanced Raman Scattering (SERS) substrate using Silicon nanowires (SiNW's) arrays, produced through chemical etching, and functionalized by tailoring their surface chemistry with nitrogen containing groups. From SEM characterization, phenomenon of micro channel formation, porosity and amorphous nature for the as prepared SiNWs was observed. Photoluminescence (PL) spectrum showed that these nanowires have broad emission band in the range of 500-900 nm. Also, change in the surface chemistry of Si nanowires after nitrogen treatment was observed by elemental analysis, EDX and X-ray photoelectron spectroscopy. The data showed that raising the modification temperature also increased the nitrogen content. At high temperature, pyridine and aromatic amines were the dominant functional groups while a small amount of quaternary nitrogen and protonated amide were also present. Methylene blue (MB) was used as a probe molecule to investigate SERS activities of functionalized SiNWs. The enhancement factor was estimated to be 107-109. Interaction of nitrogen containing groups on the surface of SiNWs with MB molecules resulted in high adsorption of MB on the substrate and higher signal detection by SERS.

Keywords: Methylene blue; photoluminescence; Raman scattering; surface enhanced Raman scattering; silicon nanowires

ABSTRAK

Kajian ini melaporkan sintesis substrak Raman Permukaan-Dipertingkatkan Sebaran (SERS) menggunakan susunan nanowayar silikon melalui proses punaran secara kimia, serta penukaran sifat kimia permukaan dengan kumpulan berfungsi bernitrogen. Melalui pencirian SEM, pembentukan saluran mikro, liang dan ciri-ciri amorfous telah diperhatikan. Spektrum fotoluminesens menunjukkan bahawa nanowayar yang terhasil mempunyai jalur pancaran lebar dalam julat 500-900 nm. Di samping itu, perubahan kimia permukaan nanowayar selepas rawatan nitrogen telah dikaji dengan analisis unsur, EDX dan spektroskopi fotoelektron sinar-X. Data yang diperoleh menunjukkan bahawa ubahsuaian melalui suhu juga meningkatkan kandungan nitrogen. Pada suhu tinggi, piridina dan amina aromatik adalah kumpulan berfungsi utama dengan terdapat kandungan kecil nitrogen kuaternari dan amida juga terbentuk. Metilena biru (MB) telah digunakan sebagai molekul model untuk mengkaji aktiviti SERS bagi substrak SiNWs yang terhasil. Faktor peningkatan sebanyak 107-109 telah diperoleh. Interaksi antara kumpulan berfungsi nitrogen pada permukaan SiNWs dan molekul MB menyebabkan penjerapan MB yang tinggi, lalu mencapai pengesanan isyarat SERS yang tinggi.

Kata kunci: Fotoluminesens; metilena biru; serakan Raman; serakan Raman permukaan dipertingkatkan; silikon nanowayar

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*Corresponding author; email: irahmad@kku.edu.sa