Sains Malaysiana 38(1): 91-94(2009)

Microstructural Characterization of Au-In Thin Film

Deposited by Electron Beam Evaporation

(Kajian Mikrostruktur Filem Nipis Au-In Diendapkan

Menggunakan Penyejatan Sinar Elektron)

Norliza Ismail, Muhammad Azmi Abdul Hamid & Azman Jalar

Pusat Pengajian Fizik Gunaan, Fakulti Sains dan Teknologi

Universiti Kebangsaan Malaysia, 43600 UKM Bangi

Selangor, Malaysia

Received:  8 April 2008 / Accepted:  6 June 2008

Abstract

The microstructure and phase formation of Au-In thin film deposited by e-beam evaporation technique has been studied. Single crystals of rocksalt were used as the  substrates. The chamber pressure during deposition was about 2.5 × 10^-5 torr and substrate temperature was 35°C. Three types of samples were prepared namely Au, In and Au-In thin films. Microstructure and chemical composition of these thin films were characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectrometer (XPS) respectively. TEM micrograph reveals island structures for both Au and In thin film on the rocksalt substrate, with the In island size distribution is about 9-30 nm compared to Au island in the range of 3-10 nm. The growth of islands instead of smooth film indicates that Au and In thin films follow the Volmer-Weber growth mode. However, island structures were not present on Au-In thin films which most probably follow the Frank van de Merwe growth mode. XPS analysis indicates intermetallic compound was not present in the Au-In thin film suggesting that diffusion process in the interface of Au and In films is minimal.

Keywords: Au-In thin film; e-beam evaporation; microstructure; TEM; XPS

Abstrak

Mikrostruktur dan pembentukan fasa bagi filem nipis Au-In yang diendapkan menggunakan teknik penyejatan alur elektron telah dikaji. Garam batu berhablur tunggal telah digunakan sebagai substrat. Tekanan kebuk semasa pengendapan adalah sekitar 2.5 x 10^-5 torr dan suhu substrat adalah pada 35°C. Tiga jenis sampel telah disediakan iaitu filem nipis Au, In dan Au-In. Mikrostruktur dan komposisi kimia filem nipis ini masing-masing dianalisis menggunakan mikroskop transmisi elektron (TEM) dan spektrometer fotoelektron sinar-X (XPS). Mikrograf TEM menunjukkan struktur pulau pada kedua-dua filem Au dan In yang diendapkan di atas substrat garam batu di mana pulau In mempunyai taburan saiz sekitar 9-30 nm berbanding dengan pulau Au iaitu 3-10 nm. Pertumbuhan berbentuk pulau berbanding lapisan sekata menunjukkan Au dan In tertumbuh mengikut mod pertumbuhan  Volmer-Weber. Walaubagaimanapun struktur pulau tidak kelihatan pada filem nipis Au-In di mana kemungkinan pertumbuhan filem Au-In adalah mengikut mod pertumbuhan Frank-van der Merwe. Analisis XPS mendapati sebatian antaralogam tidak terbentuk di dalam filem nipis Au-In, yakni mencadangkan proses resapan pada antara muka filem Au dan In adalah pada tahap minimum.

Kata kunci: Filem nipis Au-In;  mikrostruktur; penyejatan alur elektron; TEM; XPS

REFERENCES/RUJUKAN

Ay, M., Nefedov, A. & Zabel, H. 2006. Different growth modes of Au films on ZnO(0001). Surface Science 600: 5062-5067.

Chang, Z.C., Lu, F.H. & Shieu, F.S. 2001. Characterization of the microstructure and phase formation in the Au-In system using transmission electron microscopy. Materials Chemistry and Physics 70: 137-143.

Darrel, R.F. 1999. Materials issues in area-array microelectronic packaging. Journal of Materials 51(3):  22-27.

Finstad, T.G., Andreassen, T. & Olsen, T. 1975. Characterization of evaporated   gold-indium films on semiconductors. Thin Solid Films 29: 145-154.

Goral, J.P. & Eyring, L. 1986. The gold-indium thin film system: A high resolution elecron microscopy study. Journal of Less Common Metals 116: 63-72.

Ohring, M. 1992. The material science of thin films U.S.A: Academic Press Inc.

Powel, G.W. & Braun, J.D. 1964. Diffusion in the gold-indium system. Transaction of the Metallurgical Society of AIME 230: 694-699.

Simic, V. & Marinkovic, Z. 1977. Thin film interdiffusion of Au and In at room temperature. Thin Solid Films 41: 57-61.

Sze, S.M. 1985. Semiconductor devices: Physics & technology. New York: Wiley.