Spatially Resolved Impurity Identification via Temperature- and Injection-Dependent Photoluminescence Imaging

Photoluminescence-based impurity imaging methods have been shown to be able to quantify impurities with excellent detection limits of approximately 10¹⁰ cm^-3. They are, however, limited to metastable defects in p-type silicon only. In this paper, we present an approach that overcomes this limitation by evaluating temperature- and injection-dependent photoluminescence imaging. In contrast with temperature- and injection-dependent lifetime spectroscopy, we are not aiming for determining precise impurity parameters of known contaminants, but rather for identifying lifetime-limiting metal impurities using established impurity parameters from the literature. Our approach is to measure spatially resolved injection-dependent lifetimes by photoluminescence imaging and fit them with respect to established defect parameters. Additional measurements at higher temperature enhance the information content of the analysis. The two-defect approach first identifies the two lifetime-limiting defects and derives a candidate for a third defect. Subsequently, we can determine their concentrations. The presented method is not limited to doping type nor metastable defects and is, therefore, a promising method to characterize the spatially resolved distribution of a large variety of impurities.