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Abstract GaN is an important semiconductor for energy-efficient light-emitting devices. Hydrogen plays a crucial role in gallium nitride (GaN) growth and processing. It can form electrically neutral complexes with acceptors during growth, which significantly increases the acceptor incorporation. Post-growth annealing dissociates these complexes and is widely utilized for activating Mg acceptors and achieving conductive p-type GaN. In this work, we demonstrate that other acceptors, such as C and Be, also form complexes with hydrogen similar to Mg. The effect of thermal annealing of GaN on photoluminescence (PL) was investigated. In samples moderately doped with Be, the BeGa-related yellow luminescence (YLBe) band intensity decreased by up to an order of magnitude after annealing in N2ambient at temperaturesTann= 400 °C–900 °C. This was explained by the release of hydrogen from unknown traps and the passivation of the BeGaacceptors. A similar drop of PL intensity atTann= 350 °C–900 °C was observed for the CN-related YL1 band in unintentionally C-doped GaN and also attributed to passivation of the CNacceptors by hydrogen released from unknown defects. In this case, the formation of the CNHicomplexes was confirmed by the observation of the rising BL2 band associated with these complexes. AtTann> 900 °C, both the YLBeand YL1 intensities were restored, which was explained by the removal of hydrogen from the samples. Experimental results were compared to the first principles calculations of complex dissociation and hydrogen diffusion paths in GaN.
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Stability of the C N H i Complex and the Blue Luminescence Band in GaN
The dissociation of the CNHicomplex in GaN is studied in detail using photoluminescence measurements and first‐principles calculations. The blue luminescence (BL2) band with a maximum at 3.0 eV is caused by electron transitions from an excited state located at 0.02 eV below the conduction band to the ground state of the CNHidonor with the 0/+ level 0.15 eV above the valence band. The dissociation releases hydrogen atom, and the remaining CNdefect with the −/0 state at 0.92 eV above the valence band is responsible for the yellow band (YL1) with a maximum at about 2.2 eV. The dissociation of the CNHicomplex can be caused by the photoinduced defect reaction mechanism under UV illumination at low temperature (≈20 K), leading to the bleaching of the BL2 band and simultaneous rise in the YL1 band. The bleaching is reversible. Alternatively, the complex dissociates after annealing at temperatures above 600 °C. The activation energy of this process (3–4 eV, depending on the annealing geometry) corresponds to the removal of hydrogen from the sample and not to the dissociation of the complex itself.
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- Award ID(s):
- 1904861
- PAR ID:
- 10307333
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- physica status solidi (b)
- Volume:
- 258
- Issue:
- 12
- ISSN:
- 0370-1972
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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