last updated Wednesday, May 17, 2000 4:56:01 PM.
© 2000 The Materials Research Society
Verena Kirchner, Heidrun Heinke, Sven Einfeldt, Detlef Hommel
University of Bremen
Jaroslaw Z Domagala
Polish Academy of Sciences
This article was presented as part of Symposium W, "Gallium Nitride and Related Alloys" at the 1999 Fall Meeting of the Materials Research Society held in Boston, Massachusetts, November 28-December 3
The thermal expansion of different GaN samples is studied by high-resolution X-ray diffraction within the temperature range of 10 to 600 K. GaN bulk crystals, a homoepitaxial layer and different heteroepitaxial layers grown by metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) were investigated. Below 100 K the thermal expansion coefficients (TEC) were found to be nearly zero which has to be taken into account when estimating the thermal strain of GaN layers in optical experiments commonly performed at low temperatures. The homoepitaxial layer and the underlying GaN substrate with a lattice mismatch of --6x10-4 showed identical thermal expansion. The comparison between the temperature behavior of lattice parameters of heteroepitaxial layers and bulk GaN points to a superposition of thermally induced biaxial strain and compressive hydrostatic strain.
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Cite this article as: MRS Internet J. Nitride Semicond. Res. 5S1, W5.7 (2000).
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