A method for reconstructing the potential profile of surfaces covered by a dielectric layer

A method for increasing sensitivity of electrical field detection is proposed for scanning probe microscopy technique in which the distribution of the surface potential is measured simultaneously with the topography using a field-effect transistor with a nanowire channel for the case when the surface of the sample is covered by a dielectric layer that strongly attenuates the electric field of the detected electric charges. The method consists in deposition (using electron-beam physical vapor deposition) of additional resistive (Rsquare > 10kOm) chromium film of 5nm thick over a dielectric layer. Such film consists of small chromium granules separated by tunnel barriers. It was experimentally shown on the fabricated test structures that the method allows to restore the signal attenuated by the dielectric layer by 70 - 80%. The estimates showed that the sensitivity threshold of transistors integrated into the scanning probe microscope cantilever is within 2-5 mV in a single frequency band at a frequency of 100 Hz.