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While GaN is a crucial semiconductor material for bright light‐emitting devices, fabrication of p‐type GaN remains challenging since the Mg acceptor commonly used for p‐type doping is not shallow enough. Doping of GaN with Be is a promising path, yet no reliable p‐type GaN has been achieved by Be doping so far. One of the reasons is a poor understanding of point defects in Be‐doped GaN that can be studied by photoluminescence (PL). The yellow (YLBe) band at 2.15 eV is the dominant PL band in Be‐doped GaN. In this work, a blue PL band named the BLBeband is discovered. It has a maximum at 2.6 eV and a lifetime of 0.8 μs at temperatures below 100 K. The BLBeband is observed in GaN samples with relatively high concentrations of Be (>1018 cm−3). Both the YLBeand BLBebands likely originate from the isolated BeGadefect, namely from electron transitions via the −/0 and 0/+ thermodynamic transition levels of the BeGa. The 0/+ transition level is located at 0.1–0.2 eV above the valence band. Other broad PL bands in Be‐doped GaN were also observed and preliminarily attributed to Be‐containing complexes.
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Passivation of acceptors in GaN by hydrogen and their activation
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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- PAR ID:
- 10610649
- Publisher / Repository:
- IOPScience
- Date Published:
- Journal Name:
- Nanotechnology
- Volume:
- 36
- Issue:
- 10
- ISSN:
- 0957-4484
- Page Range / eLocation ID:
- 105704
- Subject(s) / Keyword(s):
- photoluminescence, passivation, defects, GaN
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1088/1361-6528/ada298
