Polarity Determination of Wurtzite and Zincblende Structures by TEM

Abstract

The applicability of transmission electron microscopy (TEM) to determine polarity was examined for GaN, ZnO, AlN and GaAs. The adopted methods are the TEM-EDS (energy dispersive X-ray spectroscopy) and the conventional convergent beam electron diffraction (CBED) methods. TEM observations and dynamical electron diffraction calculations were carried out. The results show that the CBED method is useful for ZnO and GaN, while the TEM-EDS method must be used for AlN and GaAs and can also be used for GaN and ZnO. It is clearly indicated that the TEM-EDS method is of use for the case where the difference in atomic scattering factor between the two constituent elements is small, while the CBED method is useful for the case where the difference is large.