Surface morphology and optical property of thermally annealed GaN substrates

Boule of GaN crystal was grown with 50mm diameter and 3mm thickness by hydride vapor phase epitaxy and cut using a wire saw to produce freestanding wafers. These were, mechanically polished with diamond slurry and followed with chemical mechanical polishing for final surface preparation. Surface mor...

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Bibliographic Details
Published in:Journal of crystal growth 2012-10, Vol.356, p.22-25
Main Authors: Oh, Dong Keun, Bang, Sin Young, Choi, Bong Geun, Maneeratanasarn, P., Lee, Seong Kuk, Chung, Jin Hyun, Freitas, Jaime A., Shim, Kwang Bo
Format: Article
Language:English
Subjects:
A1. Thermal annealing
A3. Hydride vapor phase epitaxy
Al. Chemical mechanical polishing
Al. Diamond mechanical polishing
Annealing
B1. Gallium nitride
Boules
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Cross-disciplinary physics: materials science
rheology
Density
Exact sciences and technology
Gallium nitrides
Growth from vapor
Materials science
Methods of crystal growth
physics of crystal growth
Morphology
Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation
Optical properties of bulk materials and thin films
Other luminescence and radiative recombination
Physics
Polished
Residual stress
Wafers
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Summary:Boule of GaN crystal was grown with 50mm diameter and 3mm thickness by hydride vapor phase epitaxy and cut using a wire saw to produce freestanding wafers. These were, mechanically polished with diamond slurry and followed with chemical mechanical polishing for final surface preparation. Surface morphology was examined by non-contact mode atomic force microscopy before and after thermal annealing process performed at 700, 800, 900, and 1000°C for 1h, in air. Wafers with optimum surface quality submitted to thermal annealing treatment at 900°C were characterized by reduced scratched density and residual stress, and surface roughness of 0.096nm. Surface quality improvement was confirmed by relatively large recovery of the room temperature near band edge luminescence intensity. ► 50mm diameter and 3mm thick GaN crystal was grown by HVPE method. ► Annealing effect was studied by AFM and PL. ► The CMP process was employed to remove the scratches and sub-surface damage. ► Surface morphology changed with the annealing temperature at 900°C. ► Optical properties have been compared through the annealing temperature.
ISSN:0022-0248
1873-5002
DOI:10.1016/j.jcrysgro.2012.06.056