A comparative study of the structural properties of InGaN/GaN quantum wells determined by X-ray diffraction, high-angle annular dark-field imaging and energy-filtered TEM
High-Angle Annular Dark-Field (HAADF) imaging is a technique that brings out compositional contrasts with a sensitivity about 106 times higher than X-ray images, thereby allowing image recording in normal STEM exposure times (a matter of minutes) instead of the time required for X-ray images (usually several hours). The technique uses those electrons that have undergone high-angle scattering. These have Z dependence and are therefore very effective in bringing out compositional contrasts.Much of the HAADF work to date has been performed on dedicated STEMs. However, the technique can be performed as well with the annular Dark-Field detector on several types of TEM/STEM systems. Such systems have the added advantage of camera-length flexibility, providing a range of images with different kinds of information from the same detector.
AbstractStructure and chemistry across the rare earth oxide-Ge interfaces of a Gd2O3-Ge-Gd2O3 heterostructure grown on p-Si (111) substrate using encapsulated solid phase epitaxy method have been studied at nanoscale using various transmission electron microscopy methods. The structure across both the interfaces was investigated using reconstructed phase and amplitude at exit plane. Chemistry across the interfaces was explored using elemental mapping, high-angle annular dark-field imaging, electron energy loss spectroscopy, and energy dispersive X-ray spectrometry. Results demonstrate the structural and chemical abruptness of both the interfaces, which is most essential to maintain the desired quantum barrier structure.
