Three-dimensional anisotropic thermal conductivity tensor of single crystalline β-Ga2O3

Jiang, Puqing; Qian, Xin; Li, Xiaobo; Yang, Ronggui

doi:10.1063/1.5054573

Cited by 109 publications

(54 citation statements)

References 37 publications

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“…14 The thermal conductivity of the Ga2O3 nano-membrane was measured as 8.4 1.0W/m-K, which is lower than the value of bulk Ga2O3 in this direction (about 13 W/m-K). 3 The thickness dependent thermal conductivity of Ga2O3 thin films from literature and this work are summarized in Figure 3. The thermal conductivity Ga2O3 thin films decreases with film thickness.…”

Section: Resultsmentioning

confidence: 99%

“…34 The blue and red lines are the bulk values in (-201) orientation and perpendicular to (100) orientation. 3,34 To understand the phonon transport across perfect Ga2O3-diamond interface, a Landauer approach [35][36][37][38] with transmission function from diffuse mismatch model (DMM) is applied to calculate the TBC at the Ga2O3-diamond interface. The general form of the Landauer formula is:…”

Section: Resultsmentioning

confidence: 99%

“…1 However, the thermal conductivity of bulk β-Ga2O3 (10-30 W/m-K, depending on crystal orientation) is at least one order of magnitude lower than those of other wide bandgap semiconductors, for instance, GaN (230 W/m-K), 4H-SiC (490 W/m-K), and diamond (>2000 W/m-K). [2][3] To utilize Ga2O3 in high frequency and high power switching applications, proper thermal management is essential to avoid device degradation due to poor thermal reliability. This will require the use of high thermal conductivity pathways to pull the heat out of the Ga2O3 devices efficiently through interfacial contacts with low thermal boundary resistance.…”

Section: Introductionmentioning

confidence: 99%

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Thermal conductance across β-Ga2O3-diamond van der Waals heterogeneous interfaces

et al. 2019

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Because of its ultra-wide bandgap, high breakdown electric field, and large-area affordable substrates grown from the melt, β-Ga2O3 has attracted great attention recently for potential applications of power electronics. However, its thermal conductivity is significantly lower than those of other wide bandgap semiconductors, such as AlN, SiC, GaN, and diamond. To ensure reliable operation with minimal self-heating at high power, proper thermal management is even more essential for Ga2O3 devices. Similarly to the past approaches aiming to alleviate selfheating in GaN high electron mobility transistors (HEMTs), a possible solution has been to integrate thin Ga2O3 membranes with diamond to fabricate Ga2O3-on-diamond lateral metalsemiconductor field-effect transistor (MESFET) or metal-oxide-semiconductor field-effect transistor (MOSFET) devices by taking advantage of the ultra-high thermal conductivity of diamond. Even though the thermal boundary conductance (TBC) between wide bandgap semiconductor devices such as GaN HEMTs and a diamond substrate is of primary importance for heat dissipation in these devices, fundamental understanding of the Ga2O3/diamond thermal interface is still missing. In this work, we study the thermal transport across the interfaces of Ga2O3 exfoliated onto a single crystal diamond. The Van der Waals bonded Ga2O3-diamond TBC is measured to be 17 -1.7/+2.0 MW/m 2 -K, which is comparable to the TBC of several physical-vapor-deposited metals on diamond. A Landauer approach is used to help understand phonon transport across perfect Ga2O3-diamond interface, which in turn sheds light on the possible TBC one could achieve with an optimized interface. A reduced thermal conductivity of the Ga2O3 nano-membrane is also observed due to additional phonon-membrane boundary scattering. The impact of the Ga2O3-substrate TBC and substrate thermal conductivity on the thermal performance of a power device are modeled and discussed. Without loss of generality, this study is not only important for Ga2O3 power electronics applications which would not be realistic without a thermal management solution, but also for the fundamental thermal science of heat transport across Van der Waals bonded interfaces.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal conductance across β-Ga2O3-diamond van der Waals heterogeneous interfaces

et al. 2019

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“…The measured thermal conductivity of the bulk (010) Ga2O3 substrate is compared with literature values as shown in Figure 2 [18][19][20] To better understand the phonon scattering mechanism in the superlattice and bulk Ga2O3, we calculate the inverse thermal diffusivity of both the superlattice and bulk Ga2O3, as shown in Figure 3 (a). The formula of inverse thermal diffusivity is shown as below:…”

Section: Resultsmentioning

confidence: 99%

Significantly reduced thermal conductivity in β -(Al0.1Ga0.9)2O3/Ga2O3 superlattices

Cheng

Tanen

Chang

et al. 2019

Applied Physics Letters

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β-Ga2O3 has emerged as a promising candidate for electronic device applications because of its ultra-wide bandgap, high breakdown electric field, and large-area affordable substrates grown from the melt. However, its thermal conductivity is at least one order of magnitude lower than that of other wide bandgap semiconductors such as SiC and GaN. Thermal dissipation in electronics made from β-Ga2O3 will be the bottleneck for real-world applications, especially for high power and high frequency devices. Similar to GaN/AlGaN interfaces, β-(AlxGa1x)2O3/Ga2O3 heterogeneous structures have been used to form a high mobility two-dimensional electron gas (2DEG) where joule heating is localized. The thermal properties of β-(AlxGa1x)2O3/Ga2O3 are the key for heat dissipation in these devices while they have not been studied before. This work reports the first measurement on thermal conductivity of β-(Al0.1Ga0.9)2O3/Ga2O3 superlattices from 80 K to 480 K. Its thermal conductivity is significantly reduced (5.7 times reduction) at room temperature comparing with that of bulk Ga2O3.Additionally, the thermal conductivity of bulk Ga2O3 with (010) orientation is measured and found to be consistent with literature values regardless of Sn doping. We discuss the phonon scattering mechanism in these structures by calculating their inverse thermal diffusivity. By comparing the estimated thermal boundary conductance (TBC) of β-(Al0.1Ga0.9)2O3/Ga2O3 interfaces and Ga2O3 maximum TBC, we reveal that some phonons in the superlattices transmit through several interfaces before scattering with other phonons or structural imperfections. This study is not only important for Ga2O3 electronics applications especially for high power and high frequency applications, but also for the fundamental thermal science of phonon transport across interfaces and in superlattices.

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“…Instead, recent reviews on β-Ga 2 O 3 point out that the identification and control of dominating (point and extended) defects is the most important step for further improvement of the properties of β-Ga 2 O 3 devices [1,3]. The low symmetry of the β-Ga 2 O 3 structure is accompanied with anisotropic thermal, electrical, and optical properties [4,5]. Theoretical work suggested already early on that the monovacancy defect of the lowest formation energy in β-Ga 2 O 3 is of a peculiar type [6], where a cation atom neighboring the cation monovacancy relaxes to an interstitial site half-way toward the vacancy [7,8].…”

Section: Introductionmentioning

confidence: 99%

Split Ga vacancies and the unusually strong anisotropy of positron annihilation spectra in β−Ga2O3

et al. 2020

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We report a systematic first-principles study on positron annihilation parameters in the β-Ga 2 O 3 lattice and Ga monovacancy defects complemented with orientation-dependent experiments of the Doppler broadening of the positron-electron annihilation. We find that both the β-Ga 2 O 3 lattice and the considered defects exhibit unusually strong anisotropy in their Doppler broadening signals. This anisotropy is associated with low symmetry of the β-Ga 2 O 3 crystal structure that leads to unusual kind of one-dimensional confinement of positrons even in the delocalized state in the lattice. In particular, the split Ga vacancies recently observed by scanning transmission electron microscopy produce unusually anisotropic positron annihilation signals. We show that in experiments, the positron annihilation signals in β-Ga 2 O 3 samples seem to be often dominated by split Ga vacancies.

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Three-dimensional anisotropic thermal conductivity tensor of single crystalline β-Ga2O3

Cited by 109 publications

References 37 publications

Thermal conductance across β-Ga2O3-diamond van der Waals heterogeneous interfaces

Thermal conductance across β-Ga2O3-diamond van der Waals heterogeneous interfaces

Significantly reduced thermal conductivity in β -(Al0.1Ga0.9)2O3/Ga2O3 superlattices

Split Ga vacancies and the unusually strong anisotropy of positron annihilation spectra in β−Ga2O3

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