The (10-10)/(2-1-12) grain boundary in nonpolar GaN:Atomic structure and influence on defect introduction

Joseph Kioseoglou 1George P. Dimitrakopulos 1Julita Smalc-Koziorowska 1,2Philomela Komninou 1Theodoros Karakostas 1

1. Dept. of Physics, Aristotle University of Thessaloniki, Thessaloniki 54 124, Greece
2. Polish Academy of Sciences, Institute of High Pressure Physics (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland


In III-Nitride compound semiconductor nanotechnology, a lot of emphasis is placed on achieving good quality epilayers grown along nonpolar and semipolar orientations, in order to reduce the polarization-induced internal electrostatic fields and the quantum-confined Stark effect. During growth of nonpolar or semipolar nitrides on r-plane or m-plane sapphire respectively, misoriented nanocrystals are introduced at the epilayer/substrate interface causing formation of threading dislocations (TDs) [1]. This phenomenon is facilitated by the high order of common symmetry conserved by the 90o<11-20> rotation which characterizes the misorientation between the nanocrystals and the matrix epilayer. In the present work we investigate by atomistic simulations, combined with high resolution transmission electron microscopy (HRTEM), the (10-10)/(2-1-12) grain boundary (GB) which was observed in a-plane GaN grown on r-plane sapphire. For the atomistic simulations a modified Stillinger –Weber empirical interatomic potential was employed. Two principal structural configurations were compared, in particular one comprising interfacial dislocations and a GB with interfacial disconnections i.e. dislocations with step character. It was found that the bicrystal comprising dislocations exhibits strain due to curvature at the points where the defects are located. On the other hand the GB comprising disconnections exhibits no curvature and is consistent the HRTEM observations. The Burgers vector of the disconnections is 1/6<2-203> as verified using circuit mapping. Due to nodal balance, two such defects can combine to give a TD emanating into the epilayer, in agreement with the experimental observations.

Acknowledgement: Support under the 7th European Framework STREP Project DOTSENSE (Grant No 224212) and MRTN-CT-2004-005583 (PARSEM) is greatly acknowledged


[1] J. Smalc-Koziorowska, G.P. Dimitrakopulos, S.-L. Sahonta, G. Tsiakatouras, A. Georgakilas, and Ph. Komninou, Appl. Phys. Lett. 89, 021910 (2008)

Legal notice
  • Legal notice:

    Copyright (c) Pielaszek Research, all rights reserved.
    The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
    In every case, proper references including Author(s) name(s) and URL of this webpage: must be provided.


Related papers
  1. Semipolar and nonpolar AlGaN growth mechanisms under N-rich conditions in PAMBE
  2. Epitaxial growth on porous substrates
  3. Epitaxial growth on porous substrates of III-V semiconductors
  4. Electron microscopy of InGaN nanorods spontaneously grown on Si (111) substrates
  5. Microstructure of InN grown on Si (111) by plasma-assisted MBE using a double buffer layer
  6. Interfacial structure of semipolar AlN grown on m-plane sapphire by PAMBE
  7. Structural models of GaN quantum dots in semipolar AlN
  8. Structural properties of quaternary InAlGaN MQWs grown by plasma-assisted MBE
  9. Study of partial dislocations in wurtzite GaN using gradient elasticity
  10. Partial dislocation core distribution in GaN using high resolution transmission electron microscopy

Presentation: Poster at E-MRS Fall Meeting 2009, Symposium C, by Philomela Komninou
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-11 14:31
Revised:   2009-06-07 00:48
© 1998-2021 pielaszek research, all rights reserved Powered by the Conference Engine