Microstrain distribution mapping on CuInSe2 thin films by means of electron backscatter diffraction, X-ray diffraction, and Raman microspectroscopy.

The investigation of the microstructure in functional, polycrystalline thin films is an important contribution to the enhanced understanding of structure-property relationships in corresponding devices. Linear and planar defects within individual grains may affect substantially the performance of the device. These defects are closely related to strain distributions. The present work compares electron and X-ray diffraction as well as Raman microspectroscopy, which provide access to microstrain distributions within individual grains. CuInSe2 thin films for solar cells are used as a model system. High-resolution electron backscatter diffraction and X-ray microdiffraction as well as Raman microspectroscopy were applied for this comparison. Consistently, microstrain values were determined of the order of 10(-4) by these three techniques. However, only electron backscatter diffraction, X-ray microdiffraction exhibit sensitivities appropriate for mapping local strain changes at the submicrometer level within individual grains in polycrystalline materials.