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Composition Control of R.F.-Sputtered Ni2MnGa Thin Films Using Optical Emission Spectroscopy
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Shyi-Kaan Wu1) and Kuan-Hua Tseng2)
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1) Department of Materials Science and Engineering, National Taiwan University
2) Department of Mechanical Engineering, National Taiwan University
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Optical emission spectroscopy can be used to monitor the composition of Ni2MnGa thin films during sputtering. By choosing peaks of Ni:341.5 nm, Mn:403.1 nm and Ga:417.2 nm, the Ar pressure is found to affect the spectrum intensities of Ni, Mn and Ga atoms, as well as the intensity ratios of IMn⁄INi and IGa⁄INi. However, the r.f. power has no obvious effect on them. This may be due to the ferromagnetic characteristic of Ni, or that different metals have different energy distributions of sputtered atoms, or that they need various p·d values to be thermalized. Here, p is the Ar pressure and d is the target and substrate distance. The intensity ratios of these peaks are found to be proportional to the composition ratios (mol ratio) of thin films with the relations: CMn⁄CNi=0.0151(IMn⁄INi)+0.392 and CGa⁄CNi=0.0720(IGa⁄INi)+0.273. Hence, the composition of sputtered thin films can be predicted by monitoring the intensity of light emission from the sputtering plasma.
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Keyword: Ni2MnGa shape memory alloys, r.f.-sputtering, optical spectroscopy, argon pressure effect
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Received: October 23, 2001
Accepted: February 25, 2002 ,
Published online: September 06, 2005 |
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Copyright (c) 2005 The Japan Institute of Metals |
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