Hydrogenated nanocrystalline silicon thin films were fabricated from Sill4 with H2 dilution at a low substrate temperature of 200℃ by the conventional plasma enhanced chemical vapor deposition technique. A high depos...Hydrogenated nanocrystalline silicon thin films were fabricated from Sill4 with H2 dilution at a low substrate temperature of 200℃ by the conventional plasma enhanced chemical vapor deposition technique. A high deposition rate over 0.75 nm/s can be achieved. Raman scattering spectral measurements revealed that the crystalline fraction and grain size increased with the increase in hydrogen dilution ratio. Fourier transform infrared spectrum measurements showed that the hydrogen content decreased and the Si-H bonding configuration changed mainly from Sill to Sill2 with the increase in hydrogen dilution ratio. This suggested that the hydrogen dilution played an important role in the low-temperature growth of nanocrystalline silicon thin film. The growth mechanism is discussed in terms of a surface diffusion model and hydrogen etching effects.展开更多
Using hybrid-functional first-principles calculation combined with the supercell method and band unfolding technique we investigate the band structure of non-strained Ge1-xSnx alloys with various Sn concentrations. Th...Using hybrid-functional first-principles calculation combined with the supercell method and band unfolding technique we investigate the band structure of non-strained Ge1-xSnx alloys with various Sn concentrations. The calculations show that at the Sn concentration of^3.1 mol% the GeSn alloy presents a direct band gap. The variation of the band structure are ascribed to the weaker electro-negativity of Sn atoms and a slight charge transfer from Sn atoms to Ge atoms.展开更多
The properties of n-Ge epilayer deposited on Si substrate with in-situ doping technology in a cold-wall ultrahigh vacuum chemical vapor deposition（UHVCVD） system are investigated.The growth temperature of 500℃ is o...The properties of n-Ge epilayer deposited on Si substrate with in-situ doping technology in a cold-wall ultrahigh vacuum chemical vapor deposition（UHVCVD） system are investigated.The growth temperature of 500℃ is optimal for the n-Ge growth in our equipment with a phosphorus concentration of 1018cm-3.In the n-Ge epilayer,the depth profile of phosphorus concentration is box-shaped and the tensile strain of 0.12% confirmed by x-ray diffraction measurement is introduced which results in the red shift of the photoluminescence.The enhancements of photoluminescence intensity with the increase of the doping concentration are observed,which is consistent with the modeling of the spontaneous emission spectrum for direct transition of Ge.The results are of significance for guiding the growth of n-Ge epilayer with in-situ doping technology.展开更多
基金supported by the Major State Basic Research and Development Program of China,Ministry of Science and Technology of China (No.G2000028208)
文摘Hydrogenated nanocrystalline silicon thin films were fabricated from Sill4 with H2 dilution at a low substrate temperature of 200℃ by the conventional plasma enhanced chemical vapor deposition technique. A high deposition rate over 0.75 nm/s can be achieved. Raman scattering spectral measurements revealed that the crystalline fraction and grain size increased with the increase in hydrogen dilution ratio. Fourier transform infrared spectrum measurements showed that the hydrogen content decreased and the Si-H bonding configuration changed mainly from Sill to Sill2 with the increase in hydrogen dilution ratio. This suggested that the hydrogen dilution played an important role in the low-temperature growth of nanocrystalline silicon thin film. The growth mechanism is discussed in terms of a surface diffusion model and hydrogen etching effects.
基金Project supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars of the State Education Ministry of China(Grant No.[2015]-1098)the Open Project of the State Key Laboratory of Surface Physics of Fudan University,the Natural Science Foundation of Guangdong Province of China(Grant No.2016A030307038)the University Innovating and Strengthening Project of Department of Education of Guangdong Province,China(Grant No.2015KTSCX090)
文摘Using hybrid-functional first-principles calculation combined with the supercell method and band unfolding technique we investigate the band structure of non-strained Ge1-xSnx alloys with various Sn concentrations. The calculations show that at the Sn concentration of^3.1 mol% the GeSn alloy presents a direct band gap. The variation of the band structure are ascribed to the weaker electro-negativity of Sn atoms and a slight charge transfer from Sn atoms to Ge atoms.
基金Project supported by the National Basic Research Program of China(Grant No.2013CB632103)the National Key Technology Support Program of China(Grant No.2015BAF24B01)+4 种基金the Natural Science Foundation of Fujian Province of China(Grant No.2016J05147)the Key Sci-Tech Research and Development Platform of Fujian Province,China(Grant No.2014H2002)the Provincial University Foundation of Fujian Province,China(Grant No.JK2013030)the Educational Youth Key Foundation of Fujian Province,China(Grant No.JA13210)the Scientific Research Fund of Fujian University of Technology,China(Grant No.GY-Z14073)
文摘The properties of n-Ge epilayer deposited on Si substrate with in-situ doping technology in a cold-wall ultrahigh vacuum chemical vapor deposition（UHVCVD） system are investigated.The growth temperature of 500℃ is optimal for the n-Ge growth in our equipment with a phosphorus concentration of 1018cm-3.In the n-Ge epilayer,the depth profile of phosphorus concentration is box-shaped and the tensile strain of 0.12% confirmed by x-ray diffraction measurement is introduced which results in the red shift of the photoluminescence.The enhancements of photoluminescence intensity with the increase of the doping concentration are observed,which is consistent with the modeling of the spontaneous emission spectrum for direct transition of Ge.The results are of significance for guiding the growth of n-Ge epilayer with in-situ doping technology.
