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Metastable Phase and Structural Transitions of Superthin Ti/Si and TiN/SiN Multilayers

Jerzy Ciosek 1Sylwia Burdyńska 2Artur Prokopiuk 2Roman Major 3Bogusław Major 3Roman Minikayev 4Tomasz R. Przesławski 1Waldemar Mróz 2

1. Institute of Electron Technology (ITE), al. Lotników 32/46, Warszawa 02-668, Poland
2. Military University of Technology, Institute of Optoelectronics (IOE), Kaliskiego 2, Warszawa 00-908, Poland
3. Polish Academy of Sciences, Institute of Metallurgy and Materials Sciences (IMIM PAN), Reymonta 25, Kraków 30-059, Poland
4. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland


Composite structures based on Ti - Si and TiNx - SiNx materials are interesting for photonic, optoelectronic and sensor techniques. The TiNx - SiNx multilayers were deposited on Si(100)-wafers by laser ablation of the Ti and Si targets in ambient nitrogen gas in range of pressures ranging from 3x10-3 to 5x10-3 mbar. The layer thickness and composition was controlled by parameters of the excimer laser pulses (wavelength at 193 nm), ambient gas species and gas pressure.
Processing of Ti - Si and TiNx - SiNx multilayers at high temperature (HT) lead to uniform metastable phase of composite films. The effect of HT treatment (typically for 10 min by rapid thermal process, RTP) at 870 K on structural transformation in multilayers were investigated by X-ray reflectrometry (XRR), X-ray diffractometry (XRD), Scanning Electron Microscopy (SEM) and ellipsometric measurements. Morphology of samples was characterised by atomic force microscopy (AFM).
The Ti - Si multilayers show the superlattice with bilayer period Λ = 31 nm and Si thickness tSi = 2.9 nm. Due to the very thin layers, the interfacial and surface energies dominate both the bulk and the strain-energy terms, which encourages the formation of metastable phase with a low interfacial energy. Then the inter facial energy term becomes less important and bulk formation energies dominate. These energetic arguments can only give a preference for phase formation and are most valid when growth occurs at near-equilibrium conditions.


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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium A, by Jerzy Ciosek
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-15 09:41
Revised:   2009-06-07 00:44