Development of Preparation Methods of SXM Tips with a Ultra-fine Probing Area

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Scanning X microscope (SXM) is a generic term various scanning microscopes which can depict the topography of sample surfaces in atomic scale by tracing the surfaces with atomically sharpened tips. While scanning the surface with the tip, a tip-sample distance is maintained constant in the SXM operation mode by keeping a physical quantity constant, which is interchanged between the tip apex and the sample surface, and strongly depends on the tip-sample distance. Thus the SXM images processed from the scanning tip tracing show the surface structures with the atomic resolution. A scanning tunneling microscope (STM) is a representative of the SXM family, which utilizes the tunneling current passing between the tip apex and the sample surface. Since the tunneling current is extremely sensitive to the tip-sample distance, even if the distance changes as small as 0.1, A, the current changes remarkably, and the atom-resolved surface images can be obtained by scanning the sample surface with a … More n atomically sharpened tip at a constant tunneling current. In addition to the STM, scanning tunneling spectroscopy (STS), an atomic force microscope (AFM), and the other scanning microscopes have been developed and advanced in a short duration. By the STS the surface state density can be imaged in the atomic resolution from the tunneling current-bias voltage characteristics, and the AFM can depict the surface topography utilizing the force exerted between the tip and the sample.However, the resolution and the reliability of the SXM images depend strongly on the tip sharpness and the stability of the atomic structure. Thus the urgent development of reliable methods to prepare and evaluate SXM tips is indispensable. In this study, using the UHV-STM/STS and the atom-probe field ion microscope combined with a field emission electron spectroscopy (A-P FIM/FEES), the characteristics and availability of the SXM tips prepared by vacuum-and electro-deposition techniques were investigated. The atomic and electronic structures of electrochemically etched Ir tips covered with Ge were studied by the A-P FIM/FEES to get information on changes in the surface states and semiconductive energy gap induced by the deposited Ge. The effects of Ge atoms adsorbed on the scanning tips can be estimated from this experiment. The surface and electronic structures of a conductive polymer were also investigated by the UHV-SnVSTS. Furthermore, the tip covered. with the conductive polymer was developed to study the detailed structures of the electronic-states of the polymer. Less