Atomic Force Microscope Laser Illumination Effects on a Sample and Its Application for Transient Spectroscopy
Gyoung H. Buh, Joseph Kopanski
A scanning capacitance microscope (SCM) is used to monitor the irradiation effect on a sample in a conventional atomic force microscope (AFM). The photo-excitation of carriers in a silicon sample caused by an AFM laser is measured from SCM capacitance-voltage curves. The sizeable amount of difference is found in SCM capacitance-voltage characteristics between under true-dark and normal condition, and is attributed to the light spillage over the cantilever's edges. The calculation shows that the direct transmission cannot be neglected in conventional AFM systems. We develop the light-induced transient spectroscopy through simple modification of a commercial SCM and demonstrate it as a tool for the measurement of a carrier lifetime with microscopic scale.