Sains Malaysiana 41(8)(2012): 993–1000

 

 

Effects of Rf Power on Structural Properties of Nc-Si:H Thin FilmsDeposited

by Layer-By-Layer (LbL) Deposition Technique

(Kesan Kuasa Rf Terhadap Sifat-Sifat Struktur Filem Nipis Nc-Si:H yang dimendapkan denganMenggunakan Teknik Lapisan Demi Lapisan (LbL)

Goh Boon Tong*, Muhamad Rasat Muhamad & Saadah Abdul Rahman

Low Dimensional Materials Research Centre, Department of Physics

University of Malaya, 50603 Kuala Lumpur, Malaysia

 

Received: 5 October 2011 / Accepted: 15 March 2012

 

 

ABSTRACT

The effects of rf power on the structural properties of hydrogenated nanocrystalline silicon (nc-Si:H) thin films deposited using layer-by-layer (LbL) deposition technique in a home-built plasma enhanced chemical vapor deposition (PECVD) system were investigated. The properties of the films were characterized by X-ray diffraction (XRD), micro-Raman scattering spectroscopy, high resolution transmission electron microscope (HRTEM) and Fourier transform infrared (FTIR) spectroscopy. The results showed that the films consisted of different size of Si crystallites embedded within an amorphous matrix and the growth of these crystallites was suppressed at higher rf powers. The crystalline volume fraction of the films was optimum at the rf power of 60 W and contained both small and big crystallites with diameters of 3.7 nm and 120 nm, respectively. The hydrogen content increased with increasing rf power and enhanced the structural disorder of the amorphous matrix thus decreasing the crystalline volume fraction of the films. Correlation of crystalline volume fraction, hydrogen content and structure disorder of the films under the effect of rf power is discussed.

 

Keywords: Crystalline volume fraction; hydrogen content; layer-by-layer deposition; ncSi:H; XRD

 

ABSTRAK

Dalam penyelidikan ini, kesan kuasa rf terhadap struktur filem nipis nanohablur silikon berhidrogen (nc-Si:H) yang dimendapkan menggunakan teknik lapisan demi lapisan (LbL) daripada sistem pemendapan wap kimia secara peningkatan plasma (PECVD) buatan sendiri telah dikaji. Sifat-sifat struktur filem nipis ini dikaji dengan kaedah belauan sinar-X (XRD), spektroskopi penyebaran mikro-Raman, mikroskopi elektron imbasan beresolusi tinggi (HRTEM) dan spektroskopi transformasi Fourier inframerah (FTIR). Keputusan menunjukkan bahawa filem nipis ini mengandungi hablur nano Si yang berlainan saiz yang terbenam dalam matriks amorfus. Pertumbuhan hablur nano Si ini terbantut pada kuasa rf yang lebih tinggi. Pecahan isi padu hablur filem nipis ini mencapai nilai optimum pada kuasa rf 60 W yang mengandungi kristalit silikon yang bersaiz kecil dan besar dengan diameter 3.7 and 120 nm. Kandungan hidrogen meningkat dengan menambahkan kuasa rf. Ini meningkatkan struktur tak tertib matriks amorfus dan pecahan isi padu hablur dalam filem nipis dapat dikurangkan. Korelasi di antara pecahan isi padu hablur, kandungan hidrogen dan struktur tak tertib filem nipis dengan kesan kuasa rf dibincangkan.

 

Kata kunci: Kandungan hydrogen; nc-Si:H; pemendapan LbL; XRD; pecahan isipadu hablur

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*Corresponding author; email: boontong77@yahoo.com

 

 

 

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