We observed the surface potential of silicon pn junctions using a Kelvin probe force microscope whose sensitivity was about five times better than that of a conventional one. It was achieved by three major improvements: electrostatic force detection using the second cantilever resonance, cantilever Q-value enhancement by operating in a vacuum, and direct cantilever resonance frequency detection using the frequency modulation technique. It was demonstrated that the surface potential of the pn junctions made by thermal diffusion varies gradually compared to those made by ion implantation, possibly reflecting their gradual dopant concentration profile.
Articles you may be interested inHigh-sensitivity quantitative Kelvin probe microscopy by noncontact ultra-high-vacuum atomic force microscopy Design and performance analysis of a threedimensional sample translation device used in ultrahigh vacuum scanned probe microscopy
The formation and observation, with reflected light, of 60-nm-diam phase-changed domains in a thin GeSbTe film using a scanning near-field optical microscope with a 785 nm wavelength laser diode is demonstrated. The dependence of the domain size on incident laser power was obtained, and the size changed from 150 to 60 nm in diameter with incident power of 8.4–7.3 mW in the probe. At the threshold power of 7.3 mW, the film temperature rose to around 180 °C to partially phase change the local area of the film from amorphous to crystalline. A detected reflectivity increase due to phase change in the formed domain was 8%–2%. The observing (reading) was performed with an incident laser power of 0.2 mW, which corresponds to 10−2–10−3 times less than in a magneto-optical recording. The incident laser power shows that the phase change reading using the reflection scanning near-field optical microscope has the potential to read the recorded bit at a speed over 10 MHz.
The possibility of SPM-based data storage is described regarding both its recording density and readout speed for ultrahigh density data storage. We consider their gap control to achieve high-speed readout. Suitable SPM-based storages are selected and their details are studied. As a result, scanning near-field optical microscope (SNOM)-and atomic force microscope (AFM)-based storages are expected to be candidates for future storage. SNOM-based storage is for 100 Gb in −2 . AFM-based storage is for 1 Tb in −2 . Using new force modulation AFM pit recording, an ultrahigh recording density of 1.2 Tb in −2 and a readout speed of 1.25 Mb s −1 are demonstrated.
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