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Electrical and Optical Properties of FeSi2 Layers
Published online by Cambridge University Press: 03 September 2012
Abstract
We fabricated α-FeSi2 and α-FeSi2 layers by using two methods: Ion Beam Synthesis (IBS) and Molecular Beam Allotaxy (MBA). In the latter technique a trapezoidal-shaped Fe profile was embedded in the Si matrix by codeposition of Si and Fe at temperatures of about 650°C. A rapid thermal anneal of the IBS and MBA samples at 1150°C for 10 s is necessary to obtain continuous α-FeSi2 layers. The Fe vacancy concentration of the α-FeSi2 layers was varied by a further anneal at lower temperatures. Resistivity measurements indicate a decrease of the resistivity with decreasing Fe vacancy concentration. The α-FeSi2 was transformed to a continuous β-FeSi2 layer by an anneal at 800°C for several hours. To investigate the nature of the band gap we performed absorption measurements at room temperature and 77 K. The analysis of the room temperature data revealed a direct transition at 0.84 eV and an additional indirect transition at 0.78 eV. At 77 K the direct transition shifts to ≈ 0.875 eV and the indirect to ≈ 0.86 eV.
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- Copyright © Materials Research Society 1994
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