Injection level lifetime spectroscopy of impurities in semiconductors

Abstract

The identification of semiconductor defects is a major task in photovoltaic and most solid state electronic technologies. A variety of techniques are used in materials analysis and many have been extensively described in the literature. Especially desirable are non-contact techniques that are sensitive to impurities in metals. Photoluminescence spectroscopy comes close to meeting this need, however it usually requires cryogenic cooling of the test specimen. The present authors have found that techniques based on measurement of recombination lifetime over a wide range of injection levels can be powerful and sensitive for materials characterisation. Not only is recombination lifetime sensitive to chemical and structural defects, but when a single defect dominates the recombination process that defect can be identified by observing the details of excess carrier decay over several orders of magnitude. This method of defect characterisation and identification will be the focus of this paper.