LAUSR

Cathodoluminescence (CL) is an important spectroscopic method for characterizing photovoltaic materials in electron microscopes. When electron-generated free carriers recombine, CL signals are emitted from the luminescent material and provide spectroscopic information that can be used to reveal features of the electronic structure, such as the band gap and defect states near the band edge. These characteristics can be correlated with the microstructure and microstructural defects that limit the solar cell efficiency. Ultimately, this knowledge can be used to develop processing schemes that optimize material structure and performance. For example, grain boundaries create interfaces in the bulk of thinfilm solar cells, leading to interfacial states may have an impact on the bulk recombination events and rates[1,2]. When investigating the influence of grain boundaries in scanning electron microscopes, the spatial resolution of CL is limited by the lateral size of the interaction volume (at least 250 nm). Much higher resolutions are needed to extract quantitative information from individual grain boundaries. Therefore, it is necessary to use high-spatial-resolution CL so that the change in electronic structure due to the interfacial states can be characterized.