Electron microscopy determination of crystallographic polarity of aluminum nitride thin films.

•The crystallographic polarity structure in AlN was examined by using several methods of TEM, and the following results were drawn.•Conventional TEM image: IDBs are observable as fringe contrast under the condition of g = 0002 excitation.•HAADF images: From the orientation of egg-shaped HAADE image of Al-N pairs, the polarity can be determined.•Scanning moire fringe pattern: Fringe pattern has a jog at IDB. The polarity can be inspected from the direction of shift of fringe at IDB.•CBED pattern: CBED pattern taken at Ea = 120 kV is applicable to the determination of polarity of AlN