ISSRNS 2012: Abstracts / Synchrotron Radiation in Natural Science Vol. 11, No 1 – 2 (2012) P 39
THERMAL EXPANSION OF GALLIUM NITRIDE
R. Minikayev1, W. Paszkowicz1∗, P. Piszora2, M. Knapp3, C. B¨ahtz4, and S. Podsiad lo5
1Institute of Physics PAS, al. Lotnikow 32/46, 02-668 Warsaw, Poland
2Faculty of Chemistry, A. Mickiewicz University, ul. Grunwaldzka 6, 60-780 Poznan, Poland
3Karlsruhe Institute of Technology, KIT (Germany), IAM-ESS Institute for Applied Materials — Energy Storage Systems, Karlsruhe, Germany
4ESRF, B.P. 220, 38043 Grenoble, France
5Faculty of Chemistry, Warsaw University of Technology, ul. Noakowskiego 3, 00-664 Warsaw, Poland
Keywords: gallium nitride, thermal expansion, lattice parameter
∗e-mail : paszk@ifpan.edu.pl
III - V nitrides such as GaN and InN and their solid solutions are basic components of modern op- toelectronic devices. Physical properties of nitride films are strongly strain-dependent. The knowledge on lattice constants at high temperatures and on thermal expansion for the bulk material is helpful in optimizing the growth conditions and in reducing the thermal strain. The existing literature data on lattice parameters and thermal expansion of gallium nitride exhibit a scatter; most often these data were determined for limited temperature intervals. In the present study, we have used a single instrument in
order to determine the thermal behavior of poly- crystalline gallium nitride in a broad temperature range. Diffraction measurements for gallium nitride fine powder were carried out at a high-resolution X-ray powder diffractometer (B2 beamline at HA- SYLAB) equipped with a helium cryostat and a graphite-heated furnace. Debye-Scherrer geometry with rotating capillary was applied. A smooth ex- perimental dependence of lattice parameter of gal- lium nitride was obtained permitting for deriving a reliable temperature variation of thermal expansion coefficient.
119
