Improvement of luminescence properties of GaN buffer layer for fast nitride scintillator structures

• Published in: Journal of crystal growth Vol. 464; pp. 221 - 225
• Main Authors: Hubáček, T., Hospodková, A., Oswald, J., Kuldová, K., Pangrác, J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.04.2017; Elsevier BV
• Subjects: A1. yellow band; A3. GaN; A3. MOVPE; B3. scintillators; Buffers; Coalescing; Crystals; Gallium nitrides; Luminescence; Nucleation; Optical properties; Optimization; Photoluminescence; Sapphire; Scintillation; Temperature; A1. yellow band; B3. scintillators; A3. GaN; A3. MOVPE
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2016.12.088

We have optimized technology of GaN buffer layer growth with respect to the application in fast scintillation structures. The deep defect luminescence so called yellow band (YB) with decay time up to tens of microseconds is undesired for these applications and should be suppressed or at least the ratio of intensities of excitonic to YB maximum has to be considerably increased. The required photoluminescence properties were achieved by optimization of growth parameters of nucleation and coalescence layer on sapphire substrate. We have shown that decrease of NH3 flow, decrease of coalescence temperature, increase of nucleation time and nucleation pressure lead to improvement of the structure and luminescence properties of the buffer layer. Results indicate a significant increased ratio of excitonic/YB luminescence intensity. •Excitonic/YB luminescence ratio of GaN buffer was 25 times increased.•Nucleation and annealing influences the excitonic intensity.•Coalescence layer influences more the yellow band luminescence.•During nucleation the strongest influence on PL was found for pressure and time.•During coalescence V/III ratio and temperature have strong influence on PL.