Nano-vibration measurements using the photoelectromotive force effect in the GaAs crystal

Abstract

A broadband, nano-vibration measuring method based on the photoelectromotive force (photo-EMF) effect of semiconductor crystal is presented. A He-Ne-laser homodyne interferometer system is used as a light source and a GaAs crystal is used as a photodetector. The signal beam, which is modulated by the vibration, interferes with the reference beam, and a vibrating interference pattern is created on the surface of the GaAs crystal. Due to the photo-EMF effect, an alternating current signal, which relates to the vibration, is produced. We found the optimum parameters for the measurements by adjustments of the intensity ratio of the two beams, the angle between the beams and the interelectrode spacing on the GaAs crystal. The system can detect the vibration amplitude about several nanometers. The results of measurements of the vibrations of the PZT sample are well coincided with those obtained by TEMPO200 (Bossa Nova Technologies, America) system.