Quasi-two-dimensional β-gallium oxide solar-blind photodetectors with ultrahigh responsivity

Oh, Sangwoo; Kim, Janghyuk; Ren, F.; Pearton, S. J.; Kim, Jihyun

doi:10.1039/c6tc02467j

Cited by 127 publications

(99 citation statements)

References 35 publications

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“…To measure the surface roughness, AFM was used to scan the diamond substrate surface and the top surface of the Ga2O3 membrane. The bottomsurface of the Ga2O3 membrane should be similar to or smoother than the top surface [26][27]. The surface images are shown inFigure 2(a-b).…”

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confidence: 99%

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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confidence: 99%

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

et al. 2019

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“…In comparison, monoclinic Ga 2 O 3 (β-Ga 2 O 3 ) possesses an intrinsic g E of 4.9 eV, corresponding to a wavelength of ~260 nm. Therefore, this PD is suitable for solar-blind detection without the need of any alloying process, making β-Ga 2 O 3 PDs better alternatives that have attracted considerable attention in the past decade [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

High-sensitivity β-Ga_2O_3 solar-blind photodetector on high-temperature pretreated c-plane sapphire substrate

Qian

Zhang

Lai

et al. 2017

Opt. Mater. Express

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thin film, which yielded a smoother surface and even a terraceand-step-like morphology on the substrate, resulting in improved crystallinity of the epitaxial film. Accordingly, both the dark and photo currents of β-Ga 2 O 3 metal-semiconductor-metal (MSM) PDs were increased by the enhanced carrier mobility (μ) of the more crystalline film. However, the substrate-annealing temperature must be sufficiently high to offset the rise of the dark current and thus achieve a remarkable improvement in the photodetection properties. As a result, the PD fabricated on the 1050 °C-annealed substrate exhibited extremely high sensitivity, for example, high responsivity (R) of 54.9 A/W and large specific detectivity (D*) of 3.71 × 10 14 Jones. Both parameters were increased by one order of magnitude because of the combined effects of the dramatic increase in μ and the effective reduction in defect-related recombination centers. Nevertheless, the latter also prolonged the recovery time of the PD. These findings suggest another way to develop β-Ga 2 O 3 PD with extremely high sensitivity.

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“…Figure b shows the Raman spectra for a thick region of a film synthesized on a sapphire substrate (after annealing). Overall, the results from both samples are shown in Table , and the position of the Raman peaks are compared with reports in the literature . As shown in Table , nine peaks are observed in the thicker regions of the films.…”

Section: Resultsmentioning

confidence: 89%

“…As such, during recent years, there have been many reports in the literature on cleaved or exfoliated β‐Ga 2 O 3 thin membranes . These membranes are typically tens to hundreds of nanometers thick and, following similar processes as those used in 2D material synthesis, can be obtained through the use of tape as an adhesive for exfoliation.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Large‐Area Nanometer‐Thin β‐Ga₂O₃ Films from Oxide Printing of Liquid Metal Gallium

Cooke

Ghadbeigi

Sun

et al. 2020

Physica Status Solidi (a)

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Herein, wafer‐scale Ga2O3 films are shown, which are synthesized by oxide printing of liquid metal Ga on SiO2/Si and sapphire substrates. This process enables highly uniform ≈2 nm‐thick films over ≫1 mm2 areas. The physical properties of these films (as‐deposited and after annealing in ambient conditions) are investigated. X‐ray photoelectron spectroscopy indicates that the as‐prepared films contain significant fractions (up to 8% wt) of Ga metal residue, which completely converts to Ga2O3 after annealing. Results from Raman spectroscopy confirm the presence of β‐phase in annealed samples. Transmission electron microscopy images indicate that the films are composed of polycrystalline domains. Photoluminescence is observed in all samples, depicting the typical spectrum of Ga2O3 with four emission bands. After annealing, the luminescence intensity increases across all samples, which is attributed to an enhancement in crystallinity. Also, the relative intensity of the blue emission decreases after annealing, which is consistent with a transition from bluish to greenish color in the films. This observation is associated with a change in defect population upon annealing. Overall, these results demonstrate that oxide printing of liquid metal gallium is a simple process that, upon annealing of the resulting films, leads to nanometer‐thin β‐Ga2O3 films over wafer‐scale areas.

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Quasi-two-dimensional β-gallium oxide solar-blind photodetectors with ultrahigh responsivity

Cited by 127 publications

References 35 publications

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

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

High-sensitivity β-Ga_2O_3 solar-blind photodetector on high-temperature pretreated c-plane sapphire substrate

Synthesis and Characterization of Large‐Area Nanometer‐Thin β‐Ga₂O₃ Films from Oxide Printing of Liquid Metal Gallium

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Quasi-two-dimensional β-gallium oxide solar-blind photodetectors with ultrahigh responsivity

Cited by 127 publications

References 35 publications

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

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

High-sensitivity β-Ga_2O_3 solar-blind photodetector on high-temperature pretreated c-plane sapphire substrate

Synthesis and Characterization of Large‐Area Nanometer‐Thin β‐Ga2O3 Films from Oxide Printing of Liquid Metal Gallium

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Synthesis and Characterization of Large‐Area Nanometer‐Thin β‐Ga₂O₃ Films from Oxide Printing of Liquid Metal Gallium