Optical characteristics of GaN single crystals grown by the HVPE : Effects of thermal annealing and N2 plasma treatment

• Published in: Journal of crystal growth Vol. 292; no. 2; pp. 206 - 211
• Main Authors: JEONG HO RYU, DONG KEUN OH, SEON TAE YOON, BONG GEUN CHOI, YOON, Jong-Won, KWANG BO SHIM
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 01-07-2006
• Subjects: Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Growth from vapor; Materials science; Methods of crystal growth; physics of crystal growth; Physics; Treatment of materials and its effects on microstructure and properties; Atomic force microscopy; Stoichiometry; Inorganic compounds; Gallium nitrides; Photoluminescence; Plasma assisted processing; 78.55.Cr A1. N2 plasma treatment; A1. Thermal annealing; Polishing; VPE; Hydrides; Crystal growth from vapors; 81.15.Gh; Damage; Thermal annealing; Temperature dependence; Binary compounds; Experimental study; Monocrystals; A3. Hydride vapor phase epitaxy; Morphology; B2. GaN; 81.40.Wx; III-V semiconductors; A1. Photoluminescence
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2006.04.017

Single-crystalline 350-mum-thick GaN were grown on 2in (0001) sapphire substrate by the hydride vapor phase epitaxy method. The free-standing bulk-like GaN crystals were obtained by delaminating from the sapphire substrate by the laser-induced lift-off technique. Mechanical polishing of the GaN crystals to remove the damage layer on their surfaces resulted in deteriorating optical properties. In order to recover the optical damages induced by the mechanical polishing, thermal annealing and N2 plasma treatment were adopted. As the annealing temperature was increased up to 900 deg C, the surface morphology and photoluminescence property of the polished GaN crystals improved, resulting from removal of the polishing-induced damage layer on the surface. Moreover, the N2 plasma treatment on the mechanically polished samples effectively removed the polishing-induced damage, leading to remarkably improve the surface morphology and photoluminescence.