Remote contact LBIC imaging of defects in semiconductors

Abstract

A high resolution and nondestructive optical technique, called “laser-beam-induced current (LBIC)”, has been developed for spatial imaging of electrically active defects in liquid phase epitaxial (LPE) HgCdTe alloy semiconductor. The technique consists of mapping the induced current between two remote contacts on the sample as a function of the incident-focused laser beam position. The induced current is a result of the charge separating effect of built-in fields in the vicinity of defects in semiconductors. The low laser power does not damage the sample, and the resolution of the technique is limited by the diffusion length of the carriers in the material. Also, since device structures such as p-n junctions are special cases of electrically active regions, LBIC imaging has been utilized to study the opto-electronic properties of these structures in a nondestructive manner, without requiring any electrical contact to the active elements. In addition, LBIC has been utilized to obtain electrical nonuniformities at the HgCdTe semiconductor surface near its interface with a ZnS passivation layer.