| Title: |
Microstructure and magnetoresistance of sputtered bismuth thin films upon annealing. |
| Authors: |
Joonyeon Chang1 presto@kist.re.kr, Hijung Kim1, Junhyun Han2, Jeon, M. H.3, Lee, W. Y.3 |
| Source: |
Journal of Applied Physics. 7/15/2005, Vol. 98 Issue 2, p023906. 7p. 4 Black and White Photographs, 4 Graphs. |
| Subject Terms: |
*BISMUTH, *ANNEALING of metals, *MICROSTRUCTURE, *SURFACES (Technology), *SPUTTERING (Physics), *MAGNETORESISTANCE, *RECRYSTALLIZATION (Metallurgy), *HEAT treatment of metals |
| Abstract: |
We investigated the microstructure and magnetotransport properties of sputtered Bi upon annealing. The grain size and the orientation of polycrystalline Bi thin films can be manipulated through a proper annealing treatment. Weak-oriented fine grains, of which size is about 0.1 μm, were found in as-sputtered Bi films. Careful annealing at 270 °C results not only in a grain growth of up to 1.1 μm but also in a [001]-preferred orientation structure. The grain size increases exponentially with annealing time in the temperature range of 266–270 °C. The grain-growth exponent (n) and the activation energy (Q) were evaluated to be 0.32±0.05 and 70.7 kJ/mol, respectively. The magnetoresistance (MR) of Bi films is strongly dependent on the microstructure and thickness of the film, and on the measured temperature. A very high MR of 30,000% can be observed in the annealed 7-μm-thick Bi films when measured at low temperature (4 K). The drastic increase in MR after annealing is largely attributed to the trigonal-axis-oriented texture diminishing anisotropy scattering as well as to the significant grain-growth decreasing grain-boundary scattering of carriers. The measured temperature and film thickness on which the phonon scattering relies are also important factors in determining the magnetoresistance of sputtered Bi films. [ABSTRACT FROM AUTHOR] |
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| Database: |
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