Comparative surface studies at atomic resolution with ultrahigh vacuum variable-temperature atomic force and scanning tunneling microscopes

With the ultrahigh vacuum variable-temperature scanning tunneling microscop e (UHV-VT-STM), atomic-level observation has been achieved. An ultrahigh va cuum atomic force microscope (UHV-AFM) has also been developed, with succes s in obtaining atom images where observation in noncontact (NC) mode with a frequency modulation (FM) detection method was attempted. Using the FM det ection method in the constant oscillation amplitude of the cantilever excit ation mode, we have obtained atomic-resolution images of Si(lll) 7 x 7 stru ctures and Si(100) 2 x 1 structures and other structures together with STM images in an ultrahigh vacuum environment. Also shown here are contact pote ntial difference (CPD) images using the NC-AFM method.