Transition of Roughness Evolution in Cu–In Alloy Films by the Formation of Intermetallic Compounds

概要

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The evolution of the surface morphology of Cu–In alloy film has been studied using an atomic force microscope. Samples of Cu–In were prepared by sequential vacuum deposition: copper was deposited to 10–40 nm thick first on a glass substrate, followed by the deposition of various amounts of indium to make the indium composition in the range of 0–75 at.%. Samples were prepared under three different conditions: A) deposited at room temperature (RT); B) deposited at RT and annealed at 120°C in vacuo; and C) deposited at 120°C. Samples formed by A and B (series A and B) showed a growth with a dynamical exponent $\beta$ of ${\sim}0.3$ while the atomic ratio In/Cu was less than 2. The formation of CuIn2 intermetallic compound was observed by X-ray diffraction as the atomic ratio approached 2. After that, $\beta$ suddenly increased to ${\sim}0.7$, which was attributed to the segregation of excess indium atoms to form cap-shaped islands. For samples grown by C (series C), the roughness initially increased more rapidly with $\beta\sim 0.7$ and decreased above $\text{In/Cu}\sim 1$. It showed a minimum at $\text{In/Cu}=2$ and finally increased again with $\beta\sim 0.7$ by forming indium islands, as in series A and B.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2005-04-15