Phase tailoring and wafer-scale uniform hetero-epitaxy of metastable-phased corundum α-Ga2O3 on sapphire

Hao, Jinggang; Ma, Tongchuan; Chen, X.H.; Kuang, Yue; Li, Li; Li, J.; Ren, Fangfang; Gu, Shulin; Tan, H. H.; Jagadish, Chennupati; Ye, J.D.

doi:10.1016/j.apsusc.2020.145871

Cited by 30 publications

(22 citation statements)

References 29 publications

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“…As the growth temperature rises, the misfit strain is rapidly released within a thin interfacial layer and the adatoms have increased thermal kinetics to reduce the energy of the whole epitaxial system. 18 The full relaxation of misfit strain was reported to facilitate the growth of β-Ga 2 O 3 , which is the most stable phase in air atmosphere. The phase transition of κ-Ga 2 O 3 is also supported by the changes of vibrational modes in Raman scattering spectra as shown in Figure S1 of the Supporting Information (SI).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Therefore, the κ-Ga 2 O 3 phase is rather stable at low temperature, mediated by the misfit-induced strain. As the growth temperature rises, the misfit strain is rapidly released within a thin interfacial layer and the adatoms have increased thermal kinetics to reduce the energy of the whole epitaxial system . The full relaxation of misfit strain was reported to facilitate the growth of β-Ga 2 O 3 , which is the most stable phase in air atmosphere.…”

Section: Resultsmentioning

confidence: 99%

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Unlocking the Single-Domain Heteroepitaxy of Orthorhombic κ-Ga₂O₃ via Phase Engineering

Zhang

Gong

Chen

et al. 2021

ACS Appl. Electron. Mater.

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The emergent ferroelectric property of κ-Ga2O3 is expected to deliver advanced functional memory and ultralow-loss transistors, while the commonly observed rotational domains in κ-Ga2O3 make the origin of ferroelectricity mysterious. In this work, the single-domain heteroepitaxy of orthorhombic κ-Ga2O3 epilayers on sapphire has been demonstrated by the halide vapor-phase epitaxy (HVPE) technique. The optimal temperature of 550 °C is energetically favorable for the stabilization of κ-Ga2O3 on sapphire without impurity phases, and the growth dynamics is dominated by the surface-reaction-limited mechanism. The evolution of microstructures and optical characteristics indicate that the κ–β phase transition occurs at an elevated temperature of over 575 °C together with a remarkable reduction of growth rate. With proper phase engineering, the single-domain κ-Ga2O3 epilayers have been ultimately achieved, exhibiting multisteps resembling a terrace morphology, a relatively low screw dislocation density of 5.2 × 107 cm–2, and reduced band tail subgap states. The single-domain structure of orthorhombic κ-Ga2O3 was identified by the XRD ϕ-scans and transmission electron microscopic analysis. The realization of single-domain epitaxy allows one to uncover the driving force for the intriguing ferroelectric behavior of κ-Ga2O3 and to design power devices with improved performance.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Unlocking the Single-Domain Heteroepitaxy of Orthorhombic κ-Ga₂O₃ via Phase Engineering

Zhang

Gong

Chen

et al. 2021

ACS Appl. Electron. Mater.

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“…This means that high-quality α-Ga 2 O 3 can be grown on inexpensive sapphire substrates. Therefore, a cost-effective effect can be obtained. , …”

Section: Introductionmentioning

confidence: 99%

“…Therefore, a cost-effective effect can be obtained. 12,13 Oda et al 14 reported that to fully utilize the high breakdown field of α-Ga 2 O 3 , the depletion region should be secured by an α-Ga 2 O 3 epilayer with a thickness of more than 5 μm. However, the 4.6% in-plane lattice mismatch and mismatched coefficient of thermal expansion between α-Ga 2 O 3 and the sapphire substrate can potentially cause a strain buildup within the α-Ga 2 O 3 epilayers, resulting in lattice distortion and dislocations.…”

Section: ■ Introductionmentioning

confidence: 99%

Heteroepitaxial Growth of Thick α-Ga₂O₃ Films on Sapphire Substrates by Flow Modulation Epitaxy with Halide Vapor Phase Epitaxy

Lee,

Cha,

Cho

et al. 2023

Crystal Growth & Design

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In this study, halide vapor phase epitaxy with flow modulation epitaxy (FME) was used to grow a 10 μm thick singlecrystalline α-Ga 2 O 3 epilayer on a sapphire substrate. By optimizing the interval time of the gas, highly crystalline thick α-Ga 2 O 3 epitaxial layers can be grown without any cracks. The as-grown α-Ga 2 O 3 was evaluated using scanning electron microscopy and atomic force microscopy to analyze the improvement in the surface morphology and roughness of the epitaxial layer, while X-ray diffraction was used to evaluate the crystallinity. Under optimized O 2 FME conditions, the thick α-Ga 2 O 3 film exhibited a lower full width at half-maximum (fwhm) of 779 arcsec for the (101̅ 4) plane compared to the (101̅ 4) plane fwhm values of 1137 and 925 arcsec obtained for the reference and HCl FME conditions, respectively. The results indicated that the α-Ga 2 O 3 epitaxial layer grown under the O 2 FME conditions exhibited the best quality. This confirms that the current approach to growing high-quality α-Ga 2 O 3 thick films is stable.

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“…Gallium oxide (Ga 2 O 3 ) is an ultrawide bandgap (UWBG) semiconductor material which has attracted much attention in the fields of power electronics and solar-blind UV photodetectors [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. Compared with other UWBG semiconductor materials such as SiC and GaN, Ga 2 O 3 has a bandgap of over 4.9 eV and a high breakdown critical field of over 8 MV/cm [ 1 , 3 , 5 ], which make it better suited for application in UV solar-blind photodetectors [ 6 , 8 , 9 , 10 ], high-power devices [ 11 , 12 , 13 , 14 ], and transparent conductive layers [ 15 , 16 ]. Generally, several distinct Ga 2 O 3 polymorphs (α, β, ε, γ, δ, and κ) can be crystallized [ 17 , 18 , 19 , 20 ].…”

Section: Introductionmentioning

confidence: 99%

A Novel Method for Growing α-Ga2O3 Films Using Mist-CVD Face-to-face Heating Plates

et al. 2022

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In this paper, the method for growing α-Ga2O3 films on c-plane sapphire substrates using an inexpensive fine-channel mist-CVD face-to-face heating plate was investigated. Because high temperatures can result in reactor deformation, expensive AlN ceramics resistant to deformation are used as the reactor fabrication material in traditional fine-channel mist-CVD equipment, which limits its use for promotion and research purposes. In this work, we used a face-to-face heating method to replace the traditional single-sided heating method which will reduce the requirement for equipment sealability. Therefore, cheap quartz can be used to replace expensive AlN ceramics to make reactors, which can greatly reduce the cost of mist-CVD equipment. We also investigated the effects of substrate temperature and carrier gas on the crystalline quality and surface morphology of α-Ga2O3 films. By optimizing the fabrication conditions, we obtained triangular grains with edges that were clearly visible in atomic force microscopy images. Using absorption spectrum analysis, we also found that the optical bandgap of the film reached 5.24 eV. Finally, we recorded a value of 508 arcsec for the full width at half maximum of the α-Ga2O3 (0006) diffraction peak in the X-ray diffraction pattern.

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Phase tailoring and wafer-scale uniform hetero-epitaxy of metastable-phased corundum α-Ga2O3 on sapphire

Cited by 30 publications

References 29 publications

Unlocking the Single-Domain Heteroepitaxy of Orthorhombic κ-Ga₂O₃ via Phase Engineering

Unlocking the Single-Domain Heteroepitaxy of Orthorhombic κ-Ga₂O₃ via Phase Engineering

Heteroepitaxial Growth of Thick α-Ga₂O₃ Films on Sapphire Substrates by Flow Modulation Epitaxy with Halide Vapor Phase Epitaxy

A Novel Method for Growing α-Ga2O3 Films Using Mist-CVD Face-to-face Heating Plates

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Phase tailoring and wafer-scale uniform hetero-epitaxy of metastable-phased corundum α-Ga2O3 on sapphire

Cited by 30 publications

References 29 publications

Unlocking the Single-Domain Heteroepitaxy of Orthorhombic κ-Ga2O3 via Phase Engineering

Unlocking the Single-Domain Heteroepitaxy of Orthorhombic κ-Ga2O3 via Phase Engineering

Heteroepitaxial Growth of Thick α-Ga2O3 Films on Sapphire Substrates by Flow Modulation Epitaxy with Halide Vapor Phase Epitaxy

A Novel Method for Growing α-Ga2O3 Films Using Mist-CVD Face-to-face Heating Plates

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Product

Resources

About

Unlocking the Single-Domain Heteroepitaxy of Orthorhombic κ-Ga₂O₃ via Phase Engineering

Unlocking the Single-Domain Heteroepitaxy of Orthorhombic κ-Ga₂O₃ via Phase Engineering

Heteroepitaxial Growth of Thick α-Ga₂O₃ Films on Sapphire Substrates by Flow Modulation Epitaxy with Halide Vapor Phase Epitaxy