High resolution imaging of contact potential difference using a novel ultrahigh vacuum non-contact atomic force microscope technique

• Published in: Applied surface science 1999-02, Vol.140 (3), p.265-270
• Main Authors: Kitamura, Shinichi, Suzuki, Katsuyuki, Iwatsuki, Masashi
• Format: Article
• Language: English
• Subjects: Ag/Si 7×7; Atomic force microscopes; Condensed matter: structure, mechanical and thermal properties; CPD; Exact sciences and technology; Force gradient; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Physics; Polypropylene; Potential image; Scanning probe microscopes, components and techniques; SKPM; Solid surfaces and solid-solid interfaces; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); UHV NC-AFM; Work function
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/S0169-4332(98)00538-8

An ultrahigh vacuum scanning Kelvin probe force microscope (UHV SKPM) based on the gradient of electrostatic force was developed using the technique of a UHV non-contact atomic force microscope (NC-AFM) capable of atomic level imaging, and used for simultaneous observation of contact potential difference (CPD) and NC-AFM images. The CPD images with a potential resolution of less than 10 meV were observed in the UHV SKPM, demonstrating an atomic level resolution. The change of potential corresponding to the charges on the insulated surface of polypropylene have been observed in UHV SKPM. We also demonstrated a reliable method to obtain the CPD from the bias voltage dependence curves of the frequency shift in all of the scanning area. The results are consistent with comparing the barrier height images in that the work functions of adatoms are greater than the work function of corner holes.