visualization of Fermi level pinning sites at metal semiconductor interfaces

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We have installed a function of ballistic electron emission microscopy (BEEM) on our ultrahigh vacuum scanning tunneling microscopy and are now checking its performance. We set up a unit composed of electrodes, electrical feedthough, and a transfer rod which are necessary for BEEM, attached it to the ultrahigh vacuum chamber, and checked they work properly. We also developed electronics for controlling the signal and adjusted computer-aided measurement system appropriately for taking the BEEM imaging and measuring I-V spectra.Since for this project it is very important to prepare metal semiconductor interfaces with a low density of interface states, we set up a glove box for the chemical processing of the samples in which concentration/density of oxygen, water and particle is extremely small. We developed a method to make samples with the ideal interface on silicon samples but for silicon carbide, which we planned to use for this study, we could not find an appropriate condition of the chemical processing for the pinning-less interface samples. We still need to work for that.We also developed a method of improving spatial resolution of atomic force microscopy (AFM) for the pinning site observation. With an intention of improving force sensitivity of AFM, we worked for reducing electrical noise and controlling the shape of the probe tip, successfully detected a single covalent chemical bonding, and took highly resolved images of silicon surfaces. We also tried for a measurement of surface potential profile imaging and confirmed that the potential imaging is taken with high sensitivity and high spatial resolutions.We also investigated the ground state structure of silicon surface, which is used to make metal semiconductor interfaces as a substrate. Using low temperature scanning tunneling microscopy (STM) with an accurate temperature measurement at the sample site, we successfully determined the structure.