Adsorption of Diatomic Molecules on Adsorption Site

• Main Authors: Sheau- Tyng Wu, 吳曉婷
• Other Authors: Deng- Sung Lin
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/28603483897518010749

碩士 === 國立交通大學 === 物理研究所 === 95 === We have observed gaseous diatomic molecule on the semiconductor surface with the chemical-physics dynamic mechanism of the chemical adsorption on the dangling bond. We explored on the phenomena in how gas molecules dissolve, how the atoms move, and on how they replace the bondings during the chemical adsorption process on the surface. By using ultra-thin scanning tip we can form desorption, or by thermal desorption and controlling the exposure of hydrogen as methods to create the paired and unpaired dangling bonds on the Si(100) surface, then we exposed gas molecules on the surface and used scanning tunneling microscopy to observe the phenomena in comparing the gas molecules before and after the adsorption with the atomic scale images. In the experiment we chose chlorine gas molecules on Si(100)-2x1:H surface as our research object. From the results shown, there were two possibilities in the structure of chemical adsorptions of gas molecules on the dangling bonds; one of them being when diatomic gas molecules come near the unpaired dangling bonds, they cause a shift in the electron cloud, forcing one chlorine atom to bond on the H-Si-Si sample surface forming H-Si-Si-Cl bonds; the other was when paired dangling bond forms, will cause the formation of weak bonds, so it will be easily broke by the chlorine atoms to form bonds, becoming Cl-Si-Si-Cl chemical adsorption. However, from the scanned STM images we can clearly see the two Cl atoms adsorbing on the Si-Si diatomic dimers.