Oxide Two‐Dimensional Electron Gas with High Mobility at Room‐Temperature

Eom, Kitae; Paik, Hanjong; Seo, Jinsol; Campbell, Neil; Tsymbal, Evgeny Y.; Oh, Sang Ho; Rzchowski, M. S.; Schlom, Darrell G.; Eom, Chang‐Beom

doi:10.1002/advs.202105652

Cited by 10 publications

(3 citation statements)

References 51 publications

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“…Also, we note that the deposition of the LSO layer did not result in a notable increase in conductivity of the SrSnO 3 channel layer, contrary to the case of BaSnO 3 that formed a 2D electron gas (2DEG) at the interface with the LSO layer. [37,39]…”

Section: Properties Of Lasco 3 Dielectric Layermentioning

confidence: 99%

Fully Deep‐UV Transparent Thin Film Transistors Based on SrSnO₃

Seo,

Kim,

Kim

et al. 2023

Adv Elect Materials

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Ultra‐wide bandgap semiconductors are gaining attention for their promising properties for UV optoelectronics and UV transparent electronics as well as high‐power applications. Among them, La‐doped SrSnO3 exhibits excellent properties both for deep‐UV transparent oxide semiconductors and deep‐UV transparent conducting oxide. Here, the demonstration of thin film transistors (TFTs) with full deep‐UV transparency is reported, including electrodes, gate oxide, and substrate. The lightly La‐doped SrSnO3 for the channel layer is grown on MgO (100) substrates with buffer layers by pulsed laser deposition. TFTs with a metal—insulator–semiconductor structure are fabricated using high‐k perovskite dielectric LaScO3 as the gate oxide. A degenerately La‐doped SrSnO3 is used as the gate, the source, and the drain electrodes to obtain good ohmic contact with the channel layer as well as UV transparency. The resultant device shows a field effect mobility value of ≈24 cm2 V−1 s−1 and an on/off ratio >106. The optical transmittance of the entire device (including the substrate) is found to be >75% at 300 nm in wavelength. Furthermore, the electrical characteristics of the device exhibit excellent stability under visible irradiation. This research highlights the potential of SrSnO3 in advancing the field of UV optoelectronics and UV transparent electronics.

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Section: Properties Of Lasco 3 Dielectric Layermentioning

confidence: 99%

Fully Deep‐UV Transparent Thin Film Transistors Based on SrSnO₃

Seo,

Kim,

Kim

et al. 2023

Adv Elect Materials

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“…[ 14 ] Recently, another similar polar interface, namely LaScO 3 /BaSnO 3 , has been investigated. [ 15,16 ]…”

Section: Introductionmentioning

confidence: 99%

“…[14] Recently, another similar polar interface, namely LaScO 3 /BaSnO 3 , has been investigated. [15,16] In this paper we report on the epitaxial growth of LaInO 3 / BaSnO 3 heterointerfaces using a SrSnO 3 buffer layer on NdScO 3 substrates. We provide clear evidence for the enhancement of the conductance at the LaInO 3 /BaSnO 3 interface for a compensated BaSnO 3 :La channel layer.…”

mentioning

confidence: 99%

Confinement of Electrons at the LaInO₃/BaSnO₃ Heterointerface

Pfützenreuter

Kim

Cho

et al. 2022

Adv Materials Inter

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temperature mobility of 320 cm 2 V −1 s −1 at a carrier density of 8.0 × 10 19 cm −3 in a bulk single crystal. [8] Furthermore, BaSnO 3 is a transparent wide bandgap semiconductor with a bandgap of 3.1 eV, which makes it suitable for high power applications like field effect transistors (FET). [9] To exploit the full potential of a FET, a 2D electron gas (2DEG) with high carrier density and mobility is highly desirable. The formation of a 2DEG at the LaInO 3 /BaSnO 3 interface was found and studied experimentally by Kim et al. in 2016 and thereafter [10,11] and has been theoretically investigated using several models. [12][13][14] Analysis of the Seebeck coefficient as well as Poisson-Schrödinger simulations suggested a thickness of ≈1 nm for the 2DEG. [14] Recently, another similar polar interface, namely LaScO 3 /BaSnO 3 , has been investigated. [15,16] In this paper we report on the epitaxial growth of LaInO 3 / BaSnO 3 heterointerfaces using a SrSnO 3 buffer layer on NdScO 3 substrates. We provide clear evidence for the enhancement of the conductance at the LaInO 3 /BaSnO 3 interface for a compensated BaSnO 3 :La channel layer. More importantly, we report on the length scale of the charge accumulation at the heterointerface and with that further support the finding of a 2DEG at the heterointerface. We also present the low temperature electrical properties of the heterointerface, displaying reduced carrier density and increased mobility Results and Discussion Structural Properties of the HeterostructureA high-resolution X-ray diffraction (HRXRD) 2θ−ω scan around the (220) NdScO 3 Bragg reflection shows three contributions, which can be attributed to the BaSnO 3 and SrSnO 3 films as well as to the NdScO 3 substrate (see Figure 1a). The SrSnO 3 film peak appears at 44.7°, which corresponds to a vertical lattice parameter of 4.056 Å. This coincides with the expected vertical lattice parameter of a fully compressively strained film, which is obtained from linear elasticity theory under the assumption of a Poisson ratio of ν = 0.23 and a lattice mismatch of 0.5% in [1-10] direction and 0.8% in [001] direction of the NdScO 3 substrate. [17] An reciprocal space mappings (RSM) measurement (Figure 1c) in the vicinity of the asymmetric (332) NdScO 3 substrate reflection exhibits the SrSnO 3 contribution directly belowThe properties of the conductance at the LaInO 3 /BaSnO 3 heterointerface are reported. The heterointerface is formed by covering the semi-insulating BaSnO 3 :La thin films with 10 nm LaInO 3 films, which are all epitaxially grown on NdScO 3 substrates. Structural properties of BaSnO 3 thin films are investigated by means of X-ray diffraction and transmission electron microscopy and exhibit a threading dislocation density of 6 × 10 10 cm −2 . Via capacitance-voltage (C-V) measurements, clear evidence is present for the accumulation of electrons at the interface within 2.5 nm in the BaSnO 3 layer, confirming the formation of a 2D electron gas (2DEG). Additionally, temperature dependent Hall effect measurem...

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Enabling 2D Electron Gas with High Room‐Temperature Electron Mobility Exceeding 100 cm² Vs⁻¹ at a Perovskite Oxide Interface

Hoffmann,

Zupancic,

Riaz

et al. 2024

Advanced Materials

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In perovskite oxide heterostructures, bulk functional properties coexist with emergent physical phenomena at epitaxial interfaces. Notably, charge transfer at the interface between two insulating oxide layers can lead to the formation of a 2D electron gas (2DEG) with possible applications in, e.g., high‐electron‐mobility transistors and ferroelectric field‐effect transistors. So far, the realization of oxide 2DEGs is, however, largely limited to the interface between the single‐crystal substrate and epitaxial film, preventing their deliberate placement inside a larger device architecture. Additionally, the substrate‐limited quality of perovskite oxide interfaces hampers room‐temperature (RT) 2DEG performance due to notoriously low electron mobility. In this work, the controlled creation of an interfacial 2DEG at the epitaxial interface between perovskite oxides BaSnO3 and LaInO3 is demonstrated with enhanced RT electron mobility values up to 119 cm2 Vs−1—the highest RT value reported so far for a perovskite oxide 2DEG. Using a combination of state‐of‐the‐art deposition modes during oxide molecular beam epitaxy, this approach opens up another degree of freedom in optimization and in situ control of the interface between two epitaxial oxide layers away from the substrate interface. Thus this approach is expected to apply to the general class of perovskite oxide 2DEG systems and to enable their improved compatibility with novel device concepts and integration across materials platforms.

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Oxide Two‐Dimensional Electron Gas with High Mobility at Room‐Temperature

Cited by 10 publications

References 51 publications

Fully Deep‐UV Transparent Thin Film Transistors Based on SrSnO₃

Fully Deep‐UV Transparent Thin Film Transistors Based on SrSnO₃

Confinement of Electrons at the LaInO₃/BaSnO₃ Heterointerface

Enabling 2D Electron Gas with High Room‐Temperature Electron Mobility Exceeding 100 cm² Vs⁻¹ at a Perovskite Oxide Interface

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Oxide Two‐Dimensional Electron Gas with High Mobility at Room‐Temperature

Cited by 10 publications

References 51 publications

Fully Deep‐UV Transparent Thin Film Transistors Based on SrSnO3

Fully Deep‐UV Transparent Thin Film Transistors Based on SrSnO3

Confinement of Electrons at the LaInO3/BaSnO3 Heterointerface

Enabling 2D Electron Gas with High Room‐Temperature Electron Mobility Exceeding 100 cm2 Vs−1 at a Perovskite Oxide Interface

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Product

Resources

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Fully Deep‐UV Transparent Thin Film Transistors Based on SrSnO₃

Fully Deep‐UV Transparent Thin Film Transistors Based on SrSnO₃

Confinement of Electrons at the LaInO₃/BaSnO₃ Heterointerface

Enabling 2D Electron Gas with High Room‐Temperature Electron Mobility Exceeding 100 cm² Vs⁻¹ at a Perovskite Oxide Interface