(274d) Quantitative Cathodoluminescence Mapping of Thin Film Semiconductors

Cathodoluminescence (CL) spectroscopy is a powerful, non-destructive, in situ microscopy technique that characterizes and maps the apparent band gap of thin film semiconductor layers, offering insight into performance metrics such as photovoltaic (PV) efficiency. While most studies present electrical film properties from CL as color mapping images, additional data analysis could lead to a deeper understanding of the films. Further analysis is often difficult due to the size of the data sets generated during dense full-spectrum CL mapping, which often necessitate trade-offs between analysis and mapping detail.

In this work, we have developed a spectral data collection and analysis technique to gather, functionalize, analyze, and generate statistical measurements from luminescence data. We utilized a set of CdMgSeTe thin films as a case study. By employing luminescence mapping and a custom R language program, we quantified the heterogeneity of the films and proved the detail underlying the wide area luminescence measurements. The statistical analysis of luminescent intensity and wavelength, spectral type curves, frequency distributions of peak wavelength, and relative intensity maps revealed a unique "luminescent fingerprint" for the films. This fingerprint can be used for quality assurance or as a response in experimental design. Our techniques can be extended to other thin film devices, highlighting the potential of spatial CL measurements and analysis to advance the field of thin film characterization.