Note: A signal-to-noise ratio enhancement based on wafer light irradiation system for optical modulation spectroscopy measurement

Abstract

We have recently found that the magnitude of the photoreflectance (PR) signal ΔR∕R on silicon wafers depends on the duration of continuous probe or pump beams irradiation. This temporal behavior of the ΔR∕R signal is attributed to the defects related electronic states at the Si∕ SiO(2) interface, which could be modified by the optical irradiation. Prior to the actual measurement, an optical irradiation of the silicon on insulator or ion implanted Si wafer can significantly enhance the signal-to-noise ratio of the PR intensity and, therefore, improve the goodness of fit. Such phenomena can be exclusively seen using a rapid detection system. A new design of the method is reported.