Study on the stress and mechanism of self-separated GaN grown by Na-flux method

Si, Zhiwei; Zong-liang, Liu; Gu, Hong; Dong, Xian-Zi; Gao, Xiaodong; Ren, Yujiao; Wang, Xiao; Wang, Jianfeng; Xu, Ke

doi:10.35848/1882-0786/abdfea

Cited by 7 publications

(3 citation statements)

References 46 publications

(47 reference statements)

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“…Figure a,b shows the Raman spectra of the GaN microdisk obtained from different test positions in GaN microdisk. It can be seen from Figure b that E 2 (high) at the points T1–T21 of the GaN microdisk is around 568.0 cm –1 , which is close to the stress-free value. − Therefore, we can further rule out that strain is the cause of this YGL. The crystalline quality characterized by the Raman result (as shown in Figure S8) is opposite to the crystal quality characterized by PL and CL (YGL/NBE), so we further ruled out the influence of the crystalline quality on the luminescence performance of the GaN microdisk.…”

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confidence: 54%

Yellow-Green Luminescence Due to Polarity-Dependent Incorporation of Carbon Impurities in Self-Assembled GaN Microdisk

Liu

et al. 2022

Nano Lett.

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Yellow-green luminescence (YGL) competes with nearbandgap emission (NBE) for carrier recombination channels, thereby reducing device efficiency; yet uncovering the origin of YGL remains a major challenge. In this paper, nearly stress-free and low dislocation density self-assembled GaN microdisks were synthesized by Na-flux method. The YGL of GaN microdisks highly depend on their polar facets. Variable accelerating voltage/power CL, variable temperature PL, and Raman spectroscopy are further performed to clarify the origin of polarity dependence of GaN microdisk YGL behavior, which indicates its independence of dislocations, surface effects, stress, crystalline quality, and gallium vacancies. It was found that the incorporation ability of carbon impurities in the polar (0001) facet is greater than that in the semipolar (101̅ 1) facets, producing higher content of C N or C N O N defects, resulting in a more pronounced YGL in the polar (0001) facet of GaN.

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confidence: 54%

Yellow-Green Luminescence Due to Polarity-Dependent Incorporation of Carbon Impurities in Self-Assembled GaN Microdisk

Liu

et al. 2022

Nano Lett.

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“…However, the graphene layer had disappeared in our study, so the path did not apply to us. Fortunately, we probably obtain self-standing GaN at the inch level using air gap-assisted separation. − We tried to use heat release adhesive to remove the epitaxial layer but did not get a whole self-standing GaN film. The possible reason is that there are too many nanoholes, and the air gap formed by the decomposition is not uniformly distributed, resulting in a larger contact area between the epilayer and the substrate, so it is more difficult to remove.…”

Section: Resultsmentioning

confidence: 99%

Study on Nucleation and Growth Mode of GaN on Patterned Graphene by Epitaxial Lateral Overgrowth

Tao

et al. 2023

Crystal Growth & Design

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In the past two decades, using dielectric materials such as SiO2 as a mask for the lateral epitaxial growth of gallium nitride (GaN) has matured, but the properties of films using amorphous mask materials are already difficult to improve, which limits the application of GaN. In this study, the quality of GaN films was enhanced by epitaxial lateral overgrowth (ELOG) on graphene mask/GaN template by metal–organic chemical vapor deposition. We found two types of nucleation and growth mode of GaN on the compound substrate and that graphene was slowly and continuously destroyed during growth. Using scanning transmission electron microscopy and Raman spectroscopy to analyze graphene between the GaN epilayer and the substrate at various periods of growth, the results showed that graphene was stable and had a distinct layer structure at the initial stage of growth, and as the growth processed, the graphene masks were disrupted due to the decomposition of the GaN substrate, and eventually air gaps of approximately 240 nm appeared at the positions of graphene masks. Although graphene is gradually decomposed, graphene masks still effectively block the dislocation from extending into the epilayer in the process, and GaN still maintains the trend of ELOG. The dislocation density of the GaN film is decreased to 1–3 × 107 cm–2, which can be estimated visually by cathodoluminescence. This feature of graphene provides a valuable strategy for the future research of large-area self-standing GaN films on GaN templates.

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“…[10][11][12] Lift-off of GaN is very important for applications in electronic and optical devices, therefore a variety of methods have been recently proposed. [13][14][15] However, in order to make use of nanovoids for lift-off applications a proper control of their formation and size is essential.…”

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Control of the formation of self-assembled nano-voids at the GaN/GaAs interface

Perez-Hernandez

Zambrano-Serrano

Gallardo-Hernández

et al. 2021

Appl. Phys. Express

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The self-assembling of nanovoids with a precisely controlled depth at the GaN/GaAs interface is reported and their formation mechanism discussed. During the very early stages of GaN growth by molecular beam epitaxy over GaAs(100) misoriented substrates, nano-pits are formed by chemical reactions of gallium and nitrogen with a GaAs sacrificial layer. The GaAs sacrificial layer is grown on top of a GaAs/AlGaAs superlattice that is used to efficiently stop the in-depth etch and to promote lateral etching. Thus, a nanostructure of wide voids and pedestals is self-assembled and confined at the interface. As an application, the lift-off of GaN epilayers from the substrate was carried out successfully, a fact that opens up the applicability of this process in other semiconductor systems.

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Study on the stress and mechanism of self-separated GaN grown by Na-flux method

Cited by 7 publications

References 46 publications

Yellow-Green Luminescence Due to Polarity-Dependent Incorporation of Carbon Impurities in Self-Assembled GaN Microdisk

Yellow-Green Luminescence Due to Polarity-Dependent Incorporation of Carbon Impurities in Self-Assembled GaN Microdisk

Study on Nucleation and Growth Mode of GaN on Patterned Graphene by Epitaxial Lateral Overgrowth

Control of the formation of self-assembled nano-voids at the GaN/GaAs interface

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