Low-temperature annealing of polycrystallineSi1-xGex after dopant implantation |
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Authors: | Zhonghe Jin Gururaj BA Yeung MWY Hoi Sing Kwok Man Wong |
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Affiliation: | Dept. of Electr. & Electron. Eng., Hong Kong Univ.; |
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Abstract: | Hall effect measurement was employed to study the isothermal annealing of boron or phosphorus implanted polycrystalline Si1-x Gex thin films, with x varying from 0.3-0.55. X-ray diffraction and cross-sectional transmission electron microscopy were used to study the crystal structure, whereas X-ray photoelectron spectroscopy was used to determine the film composition and the chemical bonding states of the elements. In low-temperature (⩽600°C) annealing, the conductivity, the dopant activation, and the Hall effect mobility decreased during extended annealing. The effective activation of phosphorus was less than 20% and decreased with increasing Ge content. Boron activation could reach above 70%. It was also found that Si1-xGex could be oxidized at 600°C in a conventional furnace even with N2 protection, especially for phosphorus doped films with high Ge content. Consequently, a low-temperature SiO2 capping layer is necessary during extended annealing |
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