AVS 46th International Symposium
    Applied Surface Science Division Tuesday Sessions
       Session AS-TuP

Paper AS-TuP10
Noncontact AFM Imaging of Al-Adsorbed Si(111) Surface

Tuesday, October 26, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: S. Orisaka, Osaka University, Japan
Authors: S. Orisaka, Osaka University, Japan
T. Minobe, Osaka University, Japan
K. Makimoto, Osaka University, Japan
Y. Sugawara, Osaka University, Japan
S. Morita, Osaka University, Japan
Correspondent: Click to Email
Recently, several groups including ourselves have reported true atomic resolution imaging using noncontact atomic force microscope (NC-AFM) operating in ultrahigh vacuum. In order to apply the NC-AFM as a scientific tool in variety of fields such as surface science, it is very important to understand the imaging mechanism of the NC-AFM on various sample surfaces. On the Si(111)7x7 reconstructed surface, we clarified that the tip-sample interaction force is dominated by the chemical bonding interaction between the dangling bond out of the Si tip apex and the dangling bond on Si adatom on the surface. In the present experiments, we investigated force interaction between an orbital of a dangling bond out of a Si tip apex and an empty orbital on a sample surface. As a sample surface with empty orbitals, Al-adsorbed Si(111) surface was used. We obtained strong contrast of NC-AFM images on Al-adsorbed Si(111) surface. Furthermore, we observed the characteristic discontinuity in the distance dependence of the frequency shift. So far, similar discontinuity has been observed on Si(111)7x7 surface, and it can be explained by the chemical bonding interaction between the dangling bond out of the Si tip apex and the dangling bond on Si adatom. So, the discontinuity in the distance dependence of the frequency shift on Al-adsorbed Si(111) surface seems to be originated from the chemical bonding interaction between an orbital of a dangling bond out of a Si tip apex and an empty orbital on a sample surface.