| Summary: | 碩士 === 國立交通大學 === 物理研究所 === 95 === We have observed in real-time the motion and behavior of hydrogen atoms on Cl-saturated Si(100)-(2x1) surfaces with temperatures ranging from 570 to 650 K using ultra-high vacuum variable-temperature scanning tunneling microscopy (STM). We have taken STM movies with and without additional exposure of hydrogen atoms onto the Cl-terminated surface. The STM images show that there were two types of H-Cl exchange movement: inter-dimer and intra-dimer. By observing the H-exposed Cl sample we traced the movements of H sites. At 570K, hydrogen atoms seldom moved and their motions were mainly single jumps. As the temperature increases, the frequency of the movement becomes higher. At 650K, hydrogen atoms move at a fast pace and multiple jumps dominate in our sequential images. We obtained similar results from the non H-exposed Cl sample. By plotting the Arrhenius relations we were able to obtain the activation energies for each set. From the set with H-exposure we obtained 1.23eV for inter-dimer hoppings and 0.70eV for intra-dimer hoppings respectively, while for the set without H-exposure we obtained 1.14eV and 0.62eV for the inter-dimer and intra-dimer hoppings respectively. Therefore, we were able to confirm from these results that the vacancies we have seen moving on the non H-exposed Si(100) Cl-terminated surface as the residual hydrogen atoms got on the surface during sample preparation and/or from the HCl impurities in the Cl2 gas source.
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