Defect physics of CuInSe_2 for photovoltaic applications using extended x-ray absorption fine structure (EXAFS)

摘要

Native point defects in undoped samples of CuInSe_2 (CIS) have been identified by a multiple-edge refinement of the extended x-ray absorption fine structure of the copper,indium and selenium absorption edges.Ab initio theoretical models for the pure compound and for various defect structures were constructed and carrier-type statistics were predicted by simultaneously fitting multiple absorption sites to these models.As expected,a model of our measurements based on pure compounds with no defects does not yield a good fit to the data.We find that a best fit requires a significant population of defects.Preliminary quantitative analysis suggests a 15% vacancy in Cu,a 2-12% population of Cu-Se anti-sites and 15% In-Se anti-sites.