Thermal Transport across Ion-Cut Monocrystalline β-Ga2O3 Thin Films and Bonded β-Ga2O3–SiC Interfaces

Cheng, Zhe; Mu, Fengwen; You, Tiangui; Xu, Wenhui; Shi, Jingjing; Liao, Michael E.; Wang, Yekan; Huynh, Karina; Suga, Tadatomo; Goorsky, Mark S.; Ou, Xin; Graham, Samuel

doi:10.1021/acsami.0c11672

Cited by 82 publications

(54 citation statements)

References 41 publications

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“…Obviously, the decrease in the thermal conductivity of the amorphous layer formed at the diamond/InGaP interface due to the amorphous layer thickness increasing in several nanometers can be ignored. In addition, the thermal boundary conductance of the Ga 2 O 3 /SiC interface with a 10 nm Al 2 O 3 interlayer was 30% lower in comparison with that of the interface with a 30 nm Al 2 O 3 interlayer, as reported in a previous study [29]. Consequently, although the amorphous layer has a certain effect on the thermal boundary conductance, the intrinsic thermal boundary conductance of the diamond/InGaP interface is the main factor to affect the heat dissipation properties of InGaP-on-diamond devices.…”

Section: Resultssupporting

confidence: 82%

Room temperature direct bonding of diamond and InGaP in atmospheric air

et al. 2021

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a new technique of diamond and inGaP room temperature bonding in atmospheric air is reported. Diamond substrate cleaned with h 2 sO 4 /h 2 O 2 mixture solution is bonded to inGaP exposed after removing the Gaas layer by the h 2 sO 4 /h 2 O 2 /h 2 O mixture solution. the bonding interface is free from interfacial voids and mechanical cracks. an atomic intermixing layer with a thickness of about 8 nm is formed at the bonding interface, which is composed of c, in, Ga, P, and O atoms. after annealing at 400 °c, no exfoliation occurred along the bonding interface. an increase of about 2 nm in the thickness of the atomic intermixing layer is observed, which plays a role in alleviating the thermal stress caused by the difference of the thermal expansion coefficient between diamond and inGaP. the bonding interface demonstrates high thermal stability to device fabrication processes. this bonding method has a large potential for bonding large diameter diamond and semiconductor materials.

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Section: Resultssupporting

confidence: 82%

Room temperature direct bonding of diamond and InGaP in atmospheric air

et al. 2021

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“…The annealing removes the ion-implantation-induced strain and restores the lattice distortion in the β-Ga2O3 layers, resulting in the increase in thermal conductivity, similar to our previous work. 14 The β-Ga2O3 thermal conductivity of Sample_N and Sample_O do not show any modulation-frequency dependence, showing that the β-Ga2O3 defect/vacancy concentrations are relatively uniform. The strong modulation frequency dependence of the measured β-Ga2O3 thermal conductivity of Sample_AB are shown in Figure 1(b).…”

Section: Resultsmentioning

confidence: 95%

“…The chamber pressure is about 0.4 Pa. More details about the bonding and ion implantation can be found in the literature. 14,15 The implanted hydrogen ions induced the exfoliation of a β-Ga2O3 thin film after heating the bonded wafers at 450 o C. The exfoliated β-Ga2O3 film is polished by CMP to a thickness of ~300 nm. Sample_AB is the as-bonded sample while Sample_N and Sample_O are annealed at 800 o C in N2 and O2, respectively.…”

Section: Discussionmentioning

confidence: 99%

Thermal Visualization of Buried Interfaces Enabled by Ratio Signal and Steady-State Heating of Time-Domain Thermoreflectance

Cheng

et al. 2021

ACS Appl. Mater. Interfaces

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Thermal resistances from interfaces impede heat dissipation in micro/nanoscale electronics, especially for high-power electronics. Despite the growing importance of understanding interfacial thermal transport, advanced thermal characterization techniques which can visualize thermal conductance across buried interfaces, especially for nonmetal-nonmetal interfaces, are still under development. This work reports a dual-modulation-frequency TDTR mapping technique to visualize the thermal conduction across buried semiconductor interfaces for β-Ga2O3-SiC samples.Both the β-Ga2O3 thermal conductivity and the buried β-Ga2O3-SiC thermal boundary conductance (TBC) are visualized for an area of 200 μm x 200 μm. Areas with low TBC values (≤20 MW/m 2 -K) are successfully identified on the TBC map, which correspond to weakly bonded interfaces caused by high-temperature annealing. The steady-state temperature rise (detector voltage), usually ignored in TDTR measurements, is found to be able to probe TBC variations of the buried interfaces without the limit of thermal penetration depth. This technique can be applied to detect defects/voids in deeply buried heterogeneous interfaces non-destructively, and also opens a door for the visualization of thermal conductance in nanoscale nonhomogeneous structures.

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“…However, mechanical exfoliation and transfer of Ga 2 O 3 are not scalable approaches for the mass production of commercial devices. Thermal transport across (2̅01)-oriented β-Ga 2 O 3 thin films heterogeneously integrated with 4H-SiC substrates via ion-cutting and surface activation bonding techniques has been demonstrated . The thermal conductivity of unintentionally doped (UID) (245 nm thick; 5.35 W/m·K) and Sn-doped (255 nm thick; 2.53 W/m·K) (2̅01)-oriented β-Ga 2 O 3 epitaxial films grown on sapphire via pulsed laser deposition (PLD) has been studied .…”

Section: Introductionmentioning

confidence: 99%

Thermal Conductivity of β-Phase Ga₂O₃ and (Al_xGa_1–_x)₂O₃ Heteroepitaxial Thin Films

Song

Ranga

Zhang

et al. 2021

ACS Appl. Mater. Interfaces

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Heteroepitaxy of β-phase gallium oxide (β-Ga 2 O 3 ) thin films on foreign substrates shows promise for the development of next-generation deep ultraviolet solar blind photodetectors and power electronic devices. In this work, the influences of the film thickness and crystallinity on the thermal conductivity of (2̅ 01)-oriented β-Ga 2 O 3 heteroepitaxial thin films were investigated. Unintentionally doped β-Ga 2 O 3 thin films were grown on c-plane sapphire substrates with off-axis angles of 0°and 6°toward ⟨112̅ 0⟩ via metal−organic vapor phase epitaxy (MOVPE) and low-pressure chemical vapor deposition. The surface morphology and crystal quality of the β-Ga 2 O 3 thin films were characterized using scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. The thermal conductivities of the β-Ga 2 O 3 films were measured via time-domain thermoreflectance. The interface quality was studied using scanning transmission electron microscopy. The measured thermal conductivities of the submicron-thick β-Ga 2 O 3 thin films were relatively low as compared to the intrinsic bulk value. The measured thin film thermal conductivities were compared with the Debye−Callaway model incorporating phononic parameters derived from first-principles calculations. The comparison suggests that the reduction in the thin film thermal conductivity can be partially attributed to the enhanced phonon-boundary scattering when the film thickness decreases. They were found to be a strong function of not only the layer thickness but also the film quality, resulting from growth on substrates with different offcut angles. Growth of β-Ga 2 O 3 films on 6°offcut sapphire substrates was found to result in higher crystallinity and thermal conductivity than films grown on on-axis c-plane sapphire. However, the β-Ga 2 O 3 films grown on 6°offcut sapphire exhibit a lower thermal boundary conductance at the β-Ga 2 O 3 / sapphire heterointerface. In addition, the thermal conductivity of MOVPE-grown (2̅ 01)-oriented β-(Al x Ga 1−x ) 2 O 3 thin films with Al compositions ranging from 2% to 43% was characterized. Because of phonon-alloy disorder scattering, the β-(Al x Ga 1−x ) 2 O 3 films exhibit lower thermal conductivities (2.8−4.7 W/m•K) than the β-Ga 2 O 3 thin films. The dominance of the alloy disorder scattering in β-(Al x Ga 1−x ) 2 O 3 is further evidenced by the weak temperature dependence of the thermal conductivity. This work provides fundamental insight into the physical interactions that govern phonon transport within heteroepitaxially grown β-phase Ga 2 O 3 and (Al x Ga 1−x ) 2 O 3 thin films and lays the groundwork for the thermal modeling and design of β-Ga 2 O 3 electronic and optoelectronic devices.

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Thermal Transport across Ion-Cut Monocrystalline β-Ga₂O₃ Thin Films and Bonded β-Ga₂O₃–SiC Interfaces

Cited by 82 publications

References 41 publications

Room temperature direct bonding of diamond and InGaP in atmospheric air

Room temperature direct bonding of diamond and InGaP in atmospheric air

Thermal Visualization of Buried Interfaces Enabled by Ratio Signal and Steady-State Heating of Time-Domain Thermoreflectance

Thermal Conductivity of β-Phase Ga₂O₃ and (Al_xGa_1–_x)₂O₃ Heteroepitaxial Thin Films

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Thermal Transport across Ion-Cut Monocrystalline β-Ga2O3 Thin Films and Bonded β-Ga2O3–SiC Interfaces

Cited by 82 publications

References 41 publications

Room temperature direct bonding of diamond and InGaP in atmospheric air

Room temperature direct bonding of diamond and InGaP in atmospheric air

Thermal Visualization of Buried Interfaces Enabled by Ratio Signal and Steady-State Heating of Time-Domain Thermoreflectance

Thermal Conductivity of β-Phase Ga2O3 and (AlxGa1–x)2O3 Heteroepitaxial Thin Films

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Product

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Thermal Transport across Ion-Cut Monocrystalline β-Ga₂O₃ Thin Films and Bonded β-Ga₂O₃–SiC Interfaces

Thermal Conductivity of β-Phase Ga₂O₃ and (Al_xGa_1–_x)₂O₃ Heteroepitaxial Thin Films