Reduction of dislocation density in GaN films on sapphire using AIN interlayers
Chaudhuri, J. George, J. T. Kolske, D. D. Wickenden, A. E. Henry, R. L. Rek, Z. U.
Chaudhuri, J.
George, J. T.
Kolske, D. D.
Wickenden, A. E.
Henry, R. L.
Rek, Z. U.
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2002-04
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Article
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Keywords
Aluminum nitride,Compressive stress,Dislocations (crystals),Film growth,Gallium nitride,Metallorganic chemical vapor deposition,Reduction,Sapphire,Single crystals,Substrates,Crystal diffractometry,Thin films
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Citation
Chaudhuri, J., George, J.T., Kolske, D.D. et al. Reduction of dislocation density in GaN films on sapphire using AIN interlayers. Journal of Materials Science 37, 1449–1453 (2002). https://doi.org/10.1023/A:1014557604325
Abstract
GaN (00.1) thin films, of thickness 1.25 to 2.25 μm grown on sapphire substrate (11.0) by metallo organic chemical vapor phase deposition (MOCVD) with different number of AIN interlayers, were characterized by triple crystal diffractometry and synchrotron white beam x-ray topography (SWBXT). The full width at half maximum (FWHM) of x-ray rocking curves from symmetric and asymmetric reflections was used to estimate the dislocation density in GaN films. It has been found that the edge dislocation density decreased from 1.63 × 1010 cm-2 to 1.23 × 1010 cm-2 and the screw dislocation density decreased from 2.0 × 108 cm-2 to 1.1 × 10-8 cm-2 when one AIN interlayer was inserted between the high temperature GaN layer. The dislocation density decreased further with the increase in number of interlayers. On the other hand the compressive stress in the GaN film increased from -0.29 GPa to -0.86 GPa. The compressive stress further increased as the number of interlayers increased but no cracking in the GaN film was observed. This could be due to better adhesion between the film and substrate due to interlayers. SWBXT in transmission from a GaN(00.1)/Al<inf>2</inf>O<inf>3</inf>(11.0) sample confirms the orientation of GaN and indicates that it is a single crystal with high dislocation density. SWBXT from the Al<inf>2</inf>O<inf>3</inf> substrate shows cellular structure of dislocations. © 2002 Kluwer Academic Publishers. © 2008 Elsevier B.V., All rights reserved.
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This is an open access article under the CC BY license.
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Springer Nature
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Journal of Materials Science
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15734803
00222461
00222461