The First Principle Studies for the Silicon ultra thin films

• Main Author: 湯鈺
• Other Authors: 林踐
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/04076292649820730882

碩士 === 國立彰化師範大學 === 光電科技研究所 === 94 === Abstract The electronic band structure of hydrogen-terminated freestanding nano-meter size (0.3nm~1.2nm) silicon ultra thin films have been calculated by the first principles in three main low-index orientations. In addition, we also study the influence of the strain on band structure and band gap of thin film with different orientation. The calculating results shows that the three orientation band gap of thin film are bigger than bulk silicon. The band gap was decreasing while increasing the film thickness. We also observed the result that the appearance of direct band gap was shown in (100), (110) ultra thin Si film. Finally, we find that the crystal strain cause the band gap reducing. In the application, ultra thin film of silicon is a promising candidate for solar cell or other optoelectronic device which is due to the reason of broad band gap and direct band gap.