Revealing silicon crystal defects by conductive atomic force microscope

The machining and polishing of silicon can damage its surface. Therefore, the investigation of the electric performance of the processed surface is of paramount importance for understanding and improving the utilization of silicon components with nanoscale crystal defects. In this study, conductivity of nanoscratches on the silicon surface was investigated using a conductive atomic force microscope. Compared to the original silicon surface (without any treatment), electrical breakover at low bias voltage could be detected on the mechanically scratched area of the silicon surface with crystal defects, and the current increased with the voltage. In contrast, no obvious current was found on the defect-free scratch created by tribochemical removal. The conductivity could also be observed on a friction-induced protrusive hillock created at high speed but not on a hillock created at low speed that is constructed by amorphous silicon. Further analysis showed that lattice distortions could facilitate easy electron flow and contributed significantly to the conductivity of a mechanical scratch on the silicon surface; however, the amorphous layer hardly contributed to the conductivity, which was also supported by high resolution transmission electron microscope analysis. As a result, the relationship between the electrical performance and microstructures was experimentally established. These findings shed new light on the subtle mechanism of defect-dependent conductivity and also provide a rapid and nondestructive method for detecting surface defects. Published by AIP Publishing.