Compact Light Illumination Module Using Laser Diode for Commercial Atomic Force Microscope

Light absorption and emission phenomena are attractive topics in a wide range of research fields, because they can be applied to the development of optoelectronic devices. Nanoscale measurement tools with light illumination are important for investigating optoelectronic properties. In this study, we design and fabricate a bottom-illumination-type compact light illumination module with a laser diode. The module is successfully installed and operated in a commercial atomic force microscope (AFM) instrument. Using this module, we can locally illuminate a MoS2 flake from the bottom and perform AFM measurements to reveal its thickness and size. In addition, photoconductive AFM (pc-AFM) can be conducted by measuring the current between the metallic tip and the sample in the dark and under illumination. The most important advantage of our light illumination module is that we can illuminate a specific sample area locally without illuminating the rest of the sample area. This module can be used for pc-AFM or Kelvin probe force microscopy study under illumination for various optoelectronic materials or devices.