Advantages of low voltage electron microscopy in semiconductor research

Abstract Investigating semiconductors free of radiation damage on a sub-nanometer scale is essential for the development of modern semiconductor technologies. The robustness of such devices is often associated with chemical impurities that mainly decorate crystallographic lattice defects. Low voltage (scanning) transmission electron microscopy (LV-(S)TEM) combines all the analytical advantages of a (S)TEM with the fact that radiation damage is avoided. In addition, the optical properties can also be determined using valence electron energy loss spectrometry (VEELS), as relativistic energy losses can also be prevented. Using GaN we demonstrate the importance of the right choice of beam energy and discuss its influence on spatial resolution, since lattice defects are very localized. For GaN we find 60 keV to the best compromise between spatial resolution and damage free analytical investigations employing VEELS and cathodoluminescence (CL) without being altered by relativistic radiation emission, such as Čerenkov-radiation and its corresponding energy losses.