Optical apparatus and method for photocarrier diffusion length measurement

摘要

An optical apparatus and method for measuring the diffusion length in an insulating photoconductor or a semiconductor sample material, that includes a source of coherent light; means for splitting the light source and providing transmitted and reflected beams each having a variable light intensity, one of the transmitted and reflected beams being incident as a background beam at a location on the sample material, means for directing the other of the transmitted and reflected beams so as to be incident at the location as a probe beam, the directing apparatus establishing a predetermined angle between the background and probe beams at the location, polarizing means disposed in the path of the background beam and having one of two predetermined orientations corresponding to polarized and non-polarized states of the beam passing therethrough, means disposed in the path of the probe beam for periodically blocking the passage thereof; and means for measuring changes in the periodic photocurrent supplied by a power source through the sample material in response to the operation of the periodic blocking apparatus for each of the polarized and non-polarized states to thereby determine the diffusion length of the sample material.