Effects of CdCl₂ treatment on the local electronic properties of polycrystalline CdTe measured with photoemission electron microscopy

To investigate the effects of CdCl$_2$ treatment on the local electronic properties of polycrystalline CdTe films, we conducted a photoemission electron microscopy (PEEM) study of polished surfaces of CdTe films in superstrate configuration, with and without CdCl$_2$ treatment. From photoemission intensity images, we observed the tendency for individual exposed grain interiors to vary in photoemission intensity, regardless of whether or not films received CdCl$_2$ treatment. Additionally, grain boundaries develop contrast in photoemission intensity images different from grain interiors after an air exposure step, similar to observations of activated grain boundaries using scanning Kelvin probe force microscopy studies. These results suggest that work function varies locally, from one grain interior to another, as well as between grain boundaries and grain interiors.