جستجوی مقالات مرتبط با کلیدواژه "سیلیکون" در نشریات گروه "فیزیک"

In this work, the damage produced in Carbon and Silicon by fast neutrons in the energy range of 0.15 to 10 MeV was calculated using TRIM code. In this range of energy, the dominant interaction is the elastic scattering. The information about recoil, nuclei energy, scattering angle and the depth in which the interaction was occurred is necessary to run TRIM code. For calculating the energy and scattering angle of recoil nuclei, the spectrum of scattered nuclei should be known. The spectrum of scattered Silicon and Carbon was calculated by using an analytical method to relate the statistical distributions to each other. Comparison of the calculated scattered spectrum with experimental one confirmed the validity of the calculation method. Calculations revealed that the damage produced in silicon is higher than the one produced in the Carbon. This is because the displacement energy threshold in Carbon is higher than the Silicon. So, using of Carbon in neutron exposure is recommended.

The accuracy of each simulating beta-voltaic battery parameter is very important, especially in micro-batteries. The aim of this study is to improve the calculation of beta-battery parameters’ accuracy. For this purpose, at first, using the Monte Carlo N-Particle code (MCNPX), the energy accumulation distribution of the 63Ni beta particle spectrum inside a silicon semiconductor has been simulated. Then, the ATLAS C-Interpreter function in C ++ was defined, using one of the SILVACO code abilities (the parameter F.RADIATE BEAM statement). Finally, the device electric parameters have been obtained using ATLAS-SILVACO based on the location-dependent of MCNPX results. For validation, the calculations were performed for a battery sample made of 16 mm2 cross-section and 1 mCi activity of radioisotope 63Ni as a source, and finally, the results were compared with one experimental result and two analytical methods. The calculations repeated for the other sample with 100 mCi activity and 1 cm2 of geometry, and compared its results with an analytical method results. The results showed that the simulation of micro-battery characteristics by the MCNPX-SILVACO hybrid code using three-dimensional electron-hole pairs’ distribution in semiconductor and the full spectrum of beta particles creates a significant increase in the accuracy of the computation, and provides a good capability to optimize the design of the battery.

Renewable energy research has created a push for new materials; one of the most attractive material in this field is quantum confined hybrid silicon nano-structures (nc-Si: H) embedded in hydrogenated amorphous silicon (a-Si: H). The essential step for this investigation is studying a-Si and its ability to produce quantum confinement (QC) in nc-Si: H. Increasing the gap of a-Si system causes solar cell efficiency to increase. By computational calculations based on Density Functional Theory (DFT)، we calculated a special localization factor، [G Allan et al.، Phys. Rev. B 57 (1997) 6933.]، for the states close to HOMO and LUMO in a-Si، and found most weak-bond Si atoms. By removing these silicon atoms and passivating the system with hydrogen، we were able to increase the gap in the a-Si system. As more than 8% hydrogenate was not experimentally available، we removed about 2% of the most localized Si atoms in the almost tetrahedral a-Si system. After removing localized Si atoms in the system with 1000 Si atoms، and adding 8% H، the gap increased about 0. 24 eV. Variation of the gap as a function of hydrogen percentage was in good agreement with the Tight –Binding results، but about 2 times more than its experimental value. This might come from the fact that in the experimental conditions، it does not have the chance to remove the most localized states. However، by improving the experimental conditions and technology، this value can be improved.