Separation of thick HVPE-GaN films from GaN templates using nanoporous GaN layers

Dong, Zengyin; Yang, Ruixia; Zhang, Song; Wang, Zaien; Chen, Jianli; Li, Xun

doi:10.1016/j.spmi.2017.08.039

Cited by 4 publications

(2 citation statements)

References 21 publications

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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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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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“…[20] During cooling, the substrate is separated by mismatch stress. Jin-Ho Kang et al [21] and Zeng Yin Dong et al [22] used a similar method to get a large freestanding GaN substrate. However, by introducing large holes, the method of releasing stress is only suitable for heterogeneous substrates.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical liftoff of freestanding GaN by a thick highly conductive sacrificial layer grown by HVPE*

Xiao¹,

Xu²,

Si³

et al. 2021

Chinese Phys. B

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Separation technology is an indispensable step in the preparation of freestanding GaN substrate. In this paper, a large-area freestanding GaN layer was separated from the substrate by an electrochemical liftoff process on a sandwich structure composed of an Fe-doped GaN substrate, a highly conductive Si-doped sacrificial layer and a top Fe-doped layer grown by hydride vapor phase epitaxy (HVPE). The large difference between the resistivity in the Si-doped layer and Fe-doped layer resulted in a sharp interface between the etched and unetched layer. It was found that the etching rate increased linearly with the applied voltage, while it continuously decreased with the electrochemical etching process as a result of the mass transport limitation. Flaky GaN pieces and nitrogen gas generated from the sacrificial layer by electrochemical etching were recognized as the main factors responsible for the blocking of the etching channel. Hence, a thick Si-doped layer grown by HVPE was used as the sacrificial layer to alleviate this problem. Moreover, high temperature and ultrasonic oscillation were also found to increase the etching rate. Based on the results above, we succeeded in the liftoff of ∼1.5 inch GaN layer. This work could help reduce the cost of freestanding GaN substrate and identifies a new way for mass production.

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Three-step growth of AlN films on sapphire substrates by metal nitride vapor phase epitaxy

Lin,

Zhang,

et al. 2024

Journal of Crystal Growth

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Separation of thick HVPE-GaN films from GaN templates using nanoporous GaN layers

Cited by 4 publications

References 21 publications

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

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

Electrochemical liftoff of freestanding GaN by a thick highly conductive sacrificial layer grown by HVPE*

Three-step growth of AlN films on sapphire substrates by metal nitride vapor phase epitaxy

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