Incoherent contrast under dynamical diffraction conditions

A dependent Bloch wave theory is used to interpret contrast in 300 keV electron incoherent channelling maps from a [013] zone of GaAs. Incoherent contrast formed by annular dark-field or backscattered electron detectors, hollow-cone illumination, or variations in emission of characteristic X-rays and bremsstrahlung, is shown to be related and accurately described by this unified theory. Methods of polarity determination from incoherent contrast are compared with diffraction contrast methods.