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We developed a multi-probe atomic force microscopy (MP-AFM) system using piezo-resistive cantilevers. The use of piezo-resistive self-sensing cantilevers with deflection sensors as probes markedly reduced complexity in the ordinary AFM setup. Simultaneous observation images can be acquired by the MP-AFM under frequency modulation (FM) detection operations. The minimum distance between these probes was 6.9μm using the piezoresistive cantilevers fabricated by a focused ion beam. Furthermore, we found that the nanoscale interaction between the probes was detected by determining the change in the amplitude of each cantilever. It was clarified that the interaction effect depended on the vibration amplitude of the cantilever-probe. [DOI: 10.1380/ejssnt.2013.13]

The performance of field effect transistors based on single-walled carbon nanotubes (SWNTs) is determined by their chirality the potential barrier at the SWNT/electrode interface, and defects in the SWNTs. Kelvin-probe force microscopy (KFM) is a powerful technique that can measure local surface potential (SP) on SWNTs for investigating local electrical properties at the interface and defects. However, the electrical potential measurement of SWNTs is often hindered by the surrounding trapped charges on the silicon oxide surface. We performed KFM imaging on an SWNT aligned between the electrodes on a silicon oxide surface by KFM using the frequency modulation (FM) method. We investigated the effect of these surface charges on the electrical potential of the SWNT measured by FM-KFM, especially in terms of the tip-sample distance. We introduced a novel two-dimensional (2D) SP mapping method in which the tip is scanned in a plane normal to the sample surface while recording the SP. The 2D SP map showed that the SP measured on the SWNT was significantly affected by the surrounding trapped charges, even when the tip-sample distance was minimized, and the electrical potential of the SWNT could not be measured accurately. [DOI: 10.1380/ejssnt.2011.210]

Atomic force microscopy (AFM) using frequency modulation (FM) detection has been widely used for the atomic scale investigations of various materials. However, high-resolution imaging in liquids by FM-AFM is severely hindered by the extreme reduction of the Q-factor due to the hydrodynamic interaction between the cantilever and the liquid. Recently the use of the small amplitude mode and the large noise reduction in the cantilever deflection sensor brought a great progress in FM-AFM imaging in liquids. In this article the details of the problems in FM-AFM imaging in liquids as well as the general directions of the improvements are described. The present status of the high-resolution FM-AFM imaging is also presented. Furthermore, future prospects and possible applications of FM-AFM in liquids are discussed.

Kelvin probe force microscopy (KFM), which has been a common method for studying electrical properties of nanometer-scale structures, is a dynamic-mode atomic force microscopy (AFM) technique combined with a traditional Kelvin probe method used for measuring macroscopic contact potential differences. It allows us to map electron affinity or work function on a nanometer scale. In this article KFM using a frequency modulation detection method (FM-KFM) is first explained briefly. The frequency modulation method plays an essential role in high-sensitive interaction force detection. We also describe applications of FM-KFM to the nanometer-scale surface potential investigations of organic materials including phase-separated self-assembled monolayer films (PS-SAM films) and single polymer crystal surfaces. Furthermore, recent results on the local surface potential study of carbon nanotube field effect transistors using FM-KFM is presented.

原子間力顕微鏡は,その最初の論文が登場して以来10年が経過し,すでに表面科学などさまざまな分野において,原子・分子スケールの分解能をもつ表面微細構造分析法として定着している。しかしながら最近においても,原子間力顕微鏡を表面のナノメートル領域における種々の物性情報を取得する手段として応用するための新規手法の開発が精力的に進められている。本稿では,この数年の間に特に進展の著しい非接触動作ダイナミックモード,単一スピンによる力の検出を目指す磁気共鳴顕微鏡,ピコ秒レベルの超高速現象をとらえる時間分解AFM,分子間力測定による材料識別法,変位センサーを内蔵する微細加工カンチレバーの開発など最近のAFM関連研究の動向について報告する。