Abstract

Near-field scanning optical microscopy (NSOM) is a very promising tool for the characterization of optical and optoelectronic properties of semiconductors and other devices at the nanometer scale [1]. Defect and impurity characterization of surfaces and interfaces is an important field in semiconductor physics. Since these materials are opaque in the visible spectral range, transmission contrast mechanisms which are most common for NSOM can not be applied in these investigations. However, near-field photocurrent (NPC) is a very attractive method for studying surface characteristics of optoelectronic devices [2,3]. The near-field laser light illumination excites electron-hole pairs directly under the fiber tip in the semiconductor material. These photoexcited carriers are collected by p-n junctions and result in a photocurrent that can be measured accurately by lock-in techniques, while moving the sample or the fiber tip to measure images.

© 1998 Optical Society of America