Instrument response of reflection high energy electron diffraction pole figure

Abstract

Reflection high-energy electron diffraction (RHEED) pole figure technique using the transmission mode has been developed to study the texture evolution of thin films. For quantitative evaluation of thin film texture, including the dispersion of texture, one would require the knowledge of the instrument response function. We report the characterization of instrument response in RHEED pole figure from an epitaxial CdTe(100) film grown on GaAs(100) substrate. We found the finite mean free path of electrons in a film contributes to the broadening of the poles. In addition, the image processing step size used in the construction of a pole figure also affects the broadening of constructed poles. We apply the measured instrument response in RHEED pole figure to quantitatively analyze a biaxially textured CdTe(111) film deposited on a biaxially textured Ge(111) substrate. Through the deconvolution of the measured dispersions from the poles in the textured CdTe(111) film by the instrument response function, we obtain the out-of-plane and in-plane dispersions of the biaxially textured CdTe(111) film. This method is generic and the instrument response should be considered in order to obtain quantitative texture information for other epitaxial and textured nanostructured films through RHEED pole figure measurements.