The influence of defects on device performance of MBE-grown Si homojunction and strained Si1-xGex/Si heterostructures |
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Authors: | D X Xu G D Shen M Willander J Knall M -A Hasan G V Hansson |
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Affiliation: | 1. Department of Physics and Measurement Technology, Link?ping University, S-581 83, Link?ping, Sweden
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Abstract: | Different Si homojunction and strained Si1-xGex/Si heterojunction diodes and bipolar transistors have been fabricated by Si-MBE. The effect of annealing on Si homojunction
diodes and transistors are studied. It is found that annealing generally improves the Si device performance, such as the ideality
factor and breakdown characteristics. The influence of60Co γ irradiation on the Si1-xGex/Si diode performances are investigated by studying the temperature dependence of their electrical characteristics, and the
results are correlated with the quality of the MBE-films. γ irradiation causes a drop in material conductivity due to the
generation of atom-displacement defects in the whole volume of the wafers and increases the defect density at hetero-interfaces.
The forward I-V curves of Si1-xGex/Si devices may shift towards lower or higher voltages, depending on the film quality and the irradiation dose. The increase
of defect density in strained Si1-xGex/Si films appears to occur easier for the films with lower quality. Electrical measurements and calculations show that the
defect-associated tunneling process is important in current transport for these MBE grown Si homojunction and strained Si1-xGex/Si heterojunction devices, which have initially medium film quality or have been treated by irradiation. |
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Keywords: | MBE strain defects misfit-dislocation Si1-xGex Si annealing γ irradiation diodes transistors |
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