Electron microscopy determination of crystallographic polarity of aluminum nitride thin films. (January 2019)

• Record Type: Journal Article
• Authors: Kuwano, Noriyuki; Kaur, Jesbains; Rahmah, Siti
• Is Part Of: Micron. Volume 116(2019)
• Page Start: 80
• Page End: 83
• Publication Date: 2019-01
• Subjects: Transmission electron microscopy -- Crystallographic polarity -- Wurtzite structure -- Aluminum nitride -- Inversion domain boundary; Microscopy -- Periodicals; Electron Probe Microanalysis -- Periodicals; Microscopy -- Periodicals; Microscopie -- Périodiques; Microscopy; Periodicals; 502.82
• DOI: 10.1016/j.micron.2018.09.014
• Languages: English
• ISSNs: 0968-4328

Abstract

Highlights: 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 E a = 120 kV is applicable to the determination of polarity of AlN Abstract: Aluminum nitride (AlN) crystallizes usually in the wurtzite structure (P63 mc) and it has a crystallographic polarity. In this work, the polarity in AlN was characterized by using several methods of transmission electron microscopy (TEM) in order to examine their applicability. AlN was deposited by metalorganic vapor phase epitaxy (MOVPE), followed by annealing at 1550 °C. TEM samples were prepared by using a focused ion beam (FIB) mill. Observation was performed with microscopes of JEM-2100, JEM-ARM200 F and FEI Titan Cubed G2 at Kyushu University (Japan), and the following results were obtained. (1) Conventional TEM imaging: Under a diffraction condition with hkil = 0002, inversion domains or an inversion domain boundary (IDB) was observed. (2) Scanning TEM (STEM) High-Angle Annular Dark Field (HAADF) imaging: Even when atomic column images of Al and N are not resolved completely from each other, the polarity was determined from the shape of atomic column images. (3) Scanning moire fringe imaging: The moire fringe pattern indicated the position of IDB and determine the direction of polarity. (4) Convergent beam electron diffraction (CBED): CBED was applicable for determination of the polarity in AlN at the acceleration voltage of 120 kV. Hence the polarity, direction of polarity and inversion domain boundary was determined using advanced TEM methods.