二源RFマグネトロンスパッタ法によるSiGe薄膜の作製と評価(<特集>電気電子工学)

概要

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Polycrystalline Si_<1-x>Ge_x films were prepared by the radio frequency magnetron sputtering method using Ar and Ar-H_2 mixture gases at substrate temperature of 500℃. The structural properties of the films were examined using Raman spectroscopy and X-ray diffraction. In the case of Ar gas sputtering, the crystalline structure of the Si_<0.25>Ge_<0.75> film was formed with good uniformity, but the Si_<0.45>Ge_<0.55> film showed the amorphous structure. On the other hand, the Si_<0.46>Ge_<0.54> film was crystallized by Ar-H_2 gas sputtering, although its crystallinity was relatively low. The H_2 gas introduction to the sputtering gas decreased the crystallization temperature. In the long wavelength range corresponding to the energy gap, the absorption coefficients of SiGe films prepared by Ar-H_2 gas sputtering showed a lower value of than those by the Ar gas sputtering. Besides, we observed the increases the activation energy from 0.14 eV to 0.17 eV. The hydrogen atoms probably reduced the dangling-bond defects or the grain-boundary defects in the films. The result suggest that the crystalline SiGe thin films have a great potential as the narrow gap material for the bottom cell of multi-junction thin film solar cells.
東海大学の論文
2005-03-31