ABSTRACT
This chapter emphasizes some of the most commonly used techniques, such as x-ray diffraction, electron diffraction, electron microscopy, crystallographic etching, and photoluminescence. High-resolution x-ray diffraction is important in the structural characterization of heteroepitaxial layers, revealing lattice constants, strains, crystallographic orientation, and defect densities. X-ray diffraction profiles from heteroepitaxial structures often exhibit interesting shapes and multiple peaks, which are difficult to interpret directly. The high-resolution x-ray diffractometers used for the characterization of heteroepitaxial semiconductors are usually of the double-axis or triple-axis type. Transmission electron microscopy is a valuable technique for the observation of dislocations, stacking faults, twin boundaries, and other crystal defects in heteroepitaxial layers. Electron beam-induced current allows the imaging of individual dislocations located in the vicinity of a p-n junction and has been employed for critical layer thickness determination. In some cases, the crystal orientation of the heteroepitaxial layer may be very different from that of the substrate, or the two crystals may even have different crystal structures.
