EMS162_Thin+Film+Diffraction_Slides

EMS162_Thin+Film+Diffraction_Slides - Types of Thin Films...

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1 2/24/2010 Thin Film Diffraction 1 Yayoi Takamura Types of Thin Films Epitaxial thin film – Single crystal film in perfect registry with underlying single crystal substrate – Often requires a high temperature growth process and a small mismatch between film and substrate material in bulk form (non-thin film case) Textured thin film – Crystalline grains have a preferential orientation in the (a) out-of-plane directions, but not in the (b) in-plane direction. Polycrystalline thin film – Thin film composed of small crystalline regions which are completely randomly oriented. – Often formed after a moderate temperature growth process and/or small to moderate mismatch between film and substrate. Amorphous thin film – Thin film with short range order but no long range order. – Often formed after low temperature growth process and/or with a large mismatch between film and substrate material, or on an amorphous substrate. (b) Top down view (a) Side view 2/24/2010 Thin Film Diffraction 2 Yayoi Takamura Types of Epitaxial Films Substrate acts as a template or seed for the orientation of the thin film Consider the {110} planes, – If the substrate is cubic, these planes are angled at 45° relative to the substrate surface – For a relaxed film, the angle is still 45 ° – For a fully strained film, the angle is something different depending on value of c film Fully strained, a film = a sub , a film c film c film a a – in-plane lattice parameter c – out-of-plane lattice parameter Fully relaxed, a film a sub , a film = c film c film a film a film
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2 2/24/2010 Thin Film Diffraction 3 Yayoi Takamura Fully Strained Films Film Substrate Tetragonally Distorted Epitaxial Film Compression Tension c a a – in-plane lattice parameter c – out-of-plane lattice parameter a film < a sub a film > a sub In bulk a
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This note was uploaded on 05/14/2010 for the course EMS 162 taught by Professor Howitt during the Spring '08 term at UC Davis.

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EMS162_Thin+Film+Diffraction_Slides - Types of Thin Films...

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