TEM-based cathodoluminescence of a Selenium-alloyed CdTe solar cell

Since 2015, commercial sample holders have been available that enable cathodoluminescence imaging of semiconductors in the TEM. Despite this, issues with low signal have meant that high resolution TEM-CL imaging has so far not been achieved on a solar cell. Here, we use xenon ion milling and cryogenic sample cooling to boost signal from the TEM foil, enabling high resolution CL imaging of a bilayer CdSeTe/CdTe solar cell for the first time. The results show that selenium has a passivation effect on grain boundaries in alloyed CdSeTe material, helping to explain the superior performance of CdSeTe solar cells.