Measurement of photoacoustic signals of depletion layer in planar metal–semiconductor–metal structure

Abstract

The photoacoustic signal from the depletion layer formed within a planar metal-semiconductor-metal (MSM) structure was detected using the photoacoustic method. To measure the distribution of the photoacoustic signal from the depletion layer, the surface of the sample was illuminated and scanned by an intensity-modulated optical beam. The amplitude and phase shifts of the observed signal increased with an increase in the reverse bias in the Schottky barrier. The intensity distribution of the photoacoustic signal corresponded closely to the position of the photocurrent distribution, showing the presence of the depletion layer as measured by the photoelectric method. This demonstrates clearly that the photoacoustic signal reflects the presence of the depletion layer in semiconductor materials, and that the photoacoustic method can be used effectively for the visualization of the depletion layer.