A Method for Reconstructing the Potential Profile of Surfaces Coated with a Dielectric Layer

I. V. Bozhev, A. S. Trifonov, D. E. Presnov, S. A. Dagesyan, A. A. Dorofeev, I. I. Tsiniaikin & V. A. Krupenin

Moscow University Physics Bulletin, 75, 1, 70-75 (2020)

We propose a method of signal amplification for the scanning probe microscope mode, in which the distribution of the surface potential of a sample is measured simultaneously with topography using a local probe based on a field-effect transistor with a nanowire channel. The application of a method is especially relevant in the study of the electric potential of the surface in the case when it is covered with a dielectric layer that strongly weakens the electric field of the detected electric charges. A key feature of the method is in additional coating the surface of the dielectric layer with thin film of chromium (Rsquare>10 kΩ; a film thickness is ∼7 nm). This film consists of small conductive granules separated by tunnel barriers. It was experimentally shown on the fabricated test structures that a signal attenuated by a dielectric layer can be restored by 70−80%. We estimated the sensitivity of transistors integrated into the probe of a scanning probe microscope in the range of 2−5 mV in single frequency band at a frequency of 100 Hz.