Measuring composition in InGaN from HAADF-STEM images and studying the temperature dependence of Z-contrast

Abstract

In this contribution, the indium concentration profile of an In xGa1-xN/GaN five-fold multi quantum well structure is measured from high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) images. The results are compared with an atom probe tomography study. Indium concentrations in the range of 26 at. to 33 at. are measured in the centre of the quantum wells. An additional indium layer of 14 at. has been found on top of the quantum wells. In the second part, the temperature dependence of measured intensities in GaN is investigated. Here, multislice calculations in the frozen lattice approximation are carried out in dependence of specimen thickness and compared to experimental data. An increase of intensity with specimen temperature is found