Investigation of semiconductor properties of Co/Si(111)-7 x 7 by AFM/KPFS

Studies of the physics underlying carrier transport characteristics and band bending of semiconductors are critical for developing new types of devices. In this work, we investigated the physical properties of Co ring-like cluster (RC) reconstruction with a low Co coverage on a Si(111)-7 x 7 surface at atomic resolution by atomic force microscopy/Kelvin probe force microscopy at 78 K. We compared the applied bias dependence of frequency shift between two types of structure: Si(111)-7 x 7 and Co-RC reconstructions. As a result, the accumulation, depletion, and reversion layers were identified in the Co-RC reconstruction by bias spectroscopy. For the first time, we found that Co-RC reconstruction on the Si(111)-7 x 7 surface shows semiconductor properties by Kelvin probe force spectroscopy. The findings of this study are useful for developing new materials for semiconductor devices.