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Reshchikov MA, Vorobiov M, Andrieiev O, Ding K, Izyumskaya N, Avrutin V, Usikov A, Helava H, Makarov Y. Determination of the concentration of impurities in GaN from photoluminescence and secondary-ion mass spectrometry. Sci Rep 2020; 10:2223. [PMID: 32041980 PMCID: PMC7010669 DOI: 10.1038/s41598-020-59033-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 01/23/2020] [Indexed: 11/09/2022] Open
Abstract
Photoluminescence (PL) was used to estimate the concentration of carbon in GaN grown by hydride vapor phase epitaxy (HVPE). The PL data were compared with profiles of the impurities obtained from secondary ion mass spectrometry (SIMS) measurements. Comparison of PL and SIMS data has revealed that apparently high concentrations of C and O at depths up to 1 µm in SIMS profiles do not represent depth distributions of these species in the GaN matrix but are rather caused by post-growth surface contamination and knocking-in impurity species from the surface. In particular, PL analysis supplemented by reactive ion etching up to the depth of 400 nm indicates that the concentration of carbon in nitrogen sites is below 2-5 × 1015 cm-3 at any depth of GaN samples grown by HVPE. We demonstrate that PL is a very sensitive and reliable tool to determine the concentrations of impurities in the GaN matrix.
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Affiliation(s)
- M A Reshchikov
- Department of Physics, Virginia Commonwealth University, Richmond, VA, 23220, USA.
| | - M Vorobiov
- Department of Physics, Virginia Commonwealth University, Richmond, VA, 23220, USA
| | - O Andrieiev
- Department of Physics, Virginia Commonwealth University, Richmond, VA, 23220, USA
| | - K Ding
- Department of Electrical Engineering and Computer Science, Virginia Commonwealth University, Richmond, VA, 23220, USA
| | - N Izyumskaya
- Department of Electrical Engineering and Computer Science, Virginia Commonwealth University, Richmond, VA, 23220, USA
| | - V Avrutin
- Department of Electrical Engineering and Computer Science, Virginia Commonwealth University, Richmond, VA, 23220, USA
| | - A Usikov
- Saint-Petersburg National Research University of Information Technologies, Mechanics and Optics, 49 Kronverkskiy Ave., 197101, Saint Petersburg, Russia
| | - H Helava
- Nitride Crystals, Inc. 9702 Gayton Road, Ste. 320, Richmond, VA, 23238, USA
| | - Yu Makarov
- Nitride Crystals, Inc. 9702 Gayton Road, Ste. 320, Richmond, VA, 23238, USA
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Abstract
Two yellow luminescence bands related to different defects have been revealed in undoped GaN grown by hydride vapor phase epitaxy (HVPE). One of them, labeled YL1, has the zero-phonon line (ZPL) at 2.57 eV and the band maximum at 2.20 eV at low temperature. This luminescence band is the ubiquitous yellow band observed in GaN grown by metalorganic chemical vapor deposition, either undoped (but containing carbon with high concentration) or doped with Si. Another yellow band, labeled YL3, has the ZPL at 2.36 eV and the band maximum at 2.09 eV. Previously, the ZPL and fine structure of this band were erroneously attributed to the red luminescence band. Both the YL1 and YL3 bands show phonon-related fine structure at the high-energy side, which is caused by strong electron-phonon coupling involving the LO and pseudo-local phonon modes. The shapes of the bands are described with a one-dimensional configuration coordinate model, and the Huang-Rhys factors are found. Possible origins of the defect-related luminescence bands are discussed.
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Reshchikov MA, Usikov A, Helava H, Makarov Y, Prozheeva V, Makkonen I, Tuomisto F, Leach JH, Udwary K. Evaluation of the concentration of point defects in GaN. Sci Rep 2017; 7:9297. [PMID: 28839151 PMCID: PMC5570983 DOI: 10.1038/s41598-017-08570-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 07/13/2017] [Indexed: 12/03/2022] Open
Abstract
Photoluminescence (PL) was used to estimate the concentration of point defects in GaN. The results are compared with data from positron annihilation spectroscopy (PAS), secondary ion mass spectrometry (SIMS), and deep level transient spectroscopy (DLTS). Defect-related PL intensity in undoped GaN grown by hydride vapor phase epitaxy increases linearly with the concentration of related defects only up to 1016 cm-3. At higher concentrations, the PL intensity associated with individual defects tends to saturate, and accordingly, does not directly correlate with the concentration of defects. For this reason, SIMS analysis, with relatively high detection limits, may not be helpful for classifying unidentified point defects in GaN. Additionally, we highlight challenges in correlating defects identified by PL with those by PAS and DLTS methods.
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Affiliation(s)
- M A Reshchikov
- Department of Physics, Virginia Commonwealth University, Richmond, VA, 23284, USA.
| | - A Usikov
- Nitride Crystals, Inc, 181E Industry Ct., Ste. B, Deer Park, NY, 11729, USA
- Saint-Petersburg National Research University of Information Technologies, Mechanics and Optics, 49 Kronverkskiy Ave, 197101, Saint Petersburg, Russia
| | - H Helava
- Nitride Crystals, Inc, 181E Industry Ct., Ste. B, Deer Park, NY, 11729, USA
| | - Yu Makarov
- Nitride Crystals, Inc, 181E Industry Ct., Ste. B, Deer Park, NY, 11729, USA
| | - V Prozheeva
- Department of Applied Physics, Aalto University, 00076, Aalto, Finland
| | - I Makkonen
- Department of Applied Physics, Aalto University, 00076, Aalto, Finland
| | - F Tuomisto
- Department of Applied Physics, Aalto University, 00076, Aalto, Finland
| | - J H Leach
- Kyma Technologies, Inc, Raleigh, North Carolina, 27617, USA
| | - K Udwary
- Kyma Technologies, Inc, Raleigh, North Carolina, 27617, USA
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Abstract
GaN-based materials are widely used for light emission devices, but the intrinsic property of wide bandgap makes it improper for photovoltaic applications. Recently, manganese was doped into GaN for absorption of visible light, and the conversion efficiency of GaN-based solar cells has been greatly improved. We conducted transient optical measurements to study the carrier dynamics of Mn-doped GaN. The lifetime of carriers in the Mn-related intermediate bands (at 1.5 eV above the valence band edge) is around 1.7 ns. The carrier relaxation within the Mn-induced bandtail states was on the order of a few hundred picoseconds. The relaxation times of different states are important parameters for optimization of conversion efficiency for intermediate-band solar cells.
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