TY - JOUR
T1 - Systematic study of shockley-read-hall and radiative recombination in GaN on Al2O3, freestanding GaN, and GaN on Si
AU - Meyer, J.
AU - Liu, R.
AU - Schaller, R. D.
AU - Lee, H. P.
AU - Bayram, C.
N1 - Funding Information:
This work is supported by the National Science Foundation Faculty Early Career Development (CAREER) Program under award number NSF-ECCS-16-52871 and partially by the Air Force Office of Scientific Research (AFOSR) through Young Investigator Program Grant FA9550-16-1-0224. J Meyer acknowledges support by the National Science Foundation Faculty Early Career Development (CAREER) Program under award number NSF ECCS 16-52871 CAR REU. R Liu acknowledges support from the NASA Space Technology Research Fellowship (NSTRF-17). This work was carried out in the Nick Holonyak, Jr Micro and Nanotechnology Laboratory and Frederick Seitz Materials Research Laboratory Central Research Facilities, University of Illinois at Urbana-Champaign, IL, USA. The authors acknowledge support from Dr Mauro Sardela, Dr Julio Soares, and Dr Tim Spila from the University of Illinois at Urbana-Champaign, IL, USA. Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U S Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
PY - 2020/6/3
Y1 - 2020/6/3
N2 - Here we study and correlate structural, electrical, and optical properties of three GaN samples: GaN grown by metalorganic chemical vapor deposition on sapphire (GaN/Al2O3), freestanding GaN crystals grown by the high nitrogen pressure solution method (HNPS GaN), and GaN grown by hydride vapor phase epitaxy on silicon (GaN/Si). Defect and impurity densities and carrier concentrations are quantified by x-ray diffraction, secondary mass ion spectroscopy, and Hall effect studies, respectively. Power-dependent photoluminescence measurements reveal GaN near-band-edge emissions from all samples having mixtures of free exciton and band-to-band transitions. Only the defect luminescence in the GaN/Si sample remains unsaturated, in contrast to those from the HNPS GaN and GaN/Al2O3 samples. Carrier lifetimes, extracted from time-resolved photoluminescence measurements, and internal quantum efficiencies, extracted from temperature-dependent photoluminescence measurements, are used to extract radiative and nonradiative lifetimes. Shockley–Read–Hall (A) and radiative recombination coefficients (B) are then calculated accordingly. Overall, the A coefficient is observed to be highly sensitive to the point defect density rather than dislocation density, as evidenced by three orders of magnitude reduction in threading dislocation density reducing the A coefficient by one order of magnitude only. The B coefficient, while comparable in the higher quality and lowly doped GaN/Al2O3 and HNPS GaN samples, was severely degraded in the GaN/Si sample due to high threading dislocation density and doping concentration.
AB - Here we study and correlate structural, electrical, and optical properties of three GaN samples: GaN grown by metalorganic chemical vapor deposition on sapphire (GaN/Al2O3), freestanding GaN crystals grown by the high nitrogen pressure solution method (HNPS GaN), and GaN grown by hydride vapor phase epitaxy on silicon (GaN/Si). Defect and impurity densities and carrier concentrations are quantified by x-ray diffraction, secondary mass ion spectroscopy, and Hall effect studies, respectively. Power-dependent photoluminescence measurements reveal GaN near-band-edge emissions from all samples having mixtures of free exciton and band-to-band transitions. Only the defect luminescence in the GaN/Si sample remains unsaturated, in contrast to those from the HNPS GaN and GaN/Al2O3 samples. Carrier lifetimes, extracted from time-resolved photoluminescence measurements, and internal quantum efficiencies, extracted from temperature-dependent photoluminescence measurements, are used to extract radiative and nonradiative lifetimes. Shockley–Read–Hall (A) and radiative recombination coefficients (B) are then calculated accordingly. Overall, the A coefficient is observed to be highly sensitive to the point defect density rather than dislocation density, as evidenced by three orders of magnitude reduction in threading dislocation density reducing the A coefficient by one order of magnitude only. The B coefficient, while comparable in the higher quality and lowly doped GaN/Al2O3 and HNPS GaN samples, was severely degraded in the GaN/Si sample due to high threading dislocation density and doping concentration.
KW - Carrier recombination
KW - Defects
KW - Excitons
KW - GaN
KW - Gallium nitride
KW - Photoluminescence
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U2 - 10.1088/2515-7647/ab9072
DO - 10.1088/2515-7647/ab9072
M3 - Article
AN - SCOPUS:85090126806
VL - 2
JO - JPhys Photonics
JF - JPhys Photonics
SN - 2515-7647
IS - 3
M1 - 035003
ER -