Quantum Confinement Effect in Amorphous In–Ga–Zn–O Heterojunction Channels for Thin-Film Transistors
Electrical and carrier transport properties in In–Ga–Zn–O thin-film transistors (IGZO TFTs) with a heterojunction channel were investigated. For the heterojunction IGZO channel, a high-In composition IGZO layer (IGZO-high-In) was deposited on a typical compositions IGZO layer (IGZO-111). From the op...
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| author | Daichi Koretomo Shuhei Hamada Yusaku Magari Mamoru Furuta |
| author_facet | Daichi Koretomo Shuhei Hamada Yusaku Magari Mamoru Furuta |
| author_sort | Daichi Koretomo |
| collection | DOAJ |
| description | Electrical and carrier transport properties in In–Ga–Zn–O thin-film transistors (IGZO TFTs) with a heterojunction channel were investigated. For the heterojunction IGZO channel, a high-In composition IGZO layer (IGZO-high-In) was deposited on a typical compositions IGZO layer (IGZO-111). From the optical properties and photoelectron yield spectroscopy measurements, the heterojunction channel was expected to have the type–II energy band diagram which possesses a conduction band offset (Δ<i>E</i><sub>c</sub>) of ~0.4 eV. A depth profile of background charge density indicated that a steep Δ<i>E</i><sub>c</sub> is formed even in the amorphous IGZO heterojunction interface deposited by sputtering. A field effect mobility (<i>μ</i><sub>FE</sub>) of bottom gate structured IGZO TFTs with the heterojunction channel (hetero-IGZO TFTs) improved to ~20 cm<sup>2</sup> V<sup>−1</sup> s<sup>−1</sup>, although a channel/gate insulator interface was formed by an IGZO−111 (<i>μ</i><sub>FE</sub> = ~12 cm<sup>2</sup> V<sup>−1</sup> s<sup>−1</sup>). Device simulation analysis revealed that the improvement of <i>μ</i><sub>FE</sub> in the hetero-IGZO TFTs was originated by a quantum confinement effect for electrons at the heterojunction interface owing to a formation of steep Δ<i>E</i><sub>c</sub>. Thus, we believe that heterojunction IGZO channel is an effective method to improve electrical properties of the TFTs. |
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| last_indexed | 2024-03-10T20:21:45Z |
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| spelling | doaj.art-dcfdac158ac745018ce13fcc9843400c2023-11-19T22:08:37ZengMDPI AGMaterials1996-19442020-04-01138193510.3390/ma13081935Quantum Confinement Effect in Amorphous In–Ga–Zn–O Heterojunction Channels for Thin-Film TransistorsDaichi Koretomo0Shuhei Hamada1Yusaku Magari2Mamoru Furuta3Engineering Course, Kochi University of Technology, Kami, Kochi 782-8502, JapanMaterial Science and Engineering Course, Kochi University of Technology, Kami, Kochi 782-8502, JapanEngineering Course, Kochi University of Technology, Kami, Kochi 782-8502, JapanEngineering Course, Kochi University of Technology, Kami, Kochi 782-8502, JapanElectrical and carrier transport properties in In–Ga–Zn–O thin-film transistors (IGZO TFTs) with a heterojunction channel were investigated. For the heterojunction IGZO channel, a high-In composition IGZO layer (IGZO-high-In) was deposited on a typical compositions IGZO layer (IGZO-111). From the optical properties and photoelectron yield spectroscopy measurements, the heterojunction channel was expected to have the type–II energy band diagram which possesses a conduction band offset (Δ<i>E</i><sub>c</sub>) of ~0.4 eV. A depth profile of background charge density indicated that a steep Δ<i>E</i><sub>c</sub> is formed even in the amorphous IGZO heterojunction interface deposited by sputtering. A field effect mobility (<i>μ</i><sub>FE</sub>) of bottom gate structured IGZO TFTs with the heterojunction channel (hetero-IGZO TFTs) improved to ~20 cm<sup>2</sup> V<sup>−1</sup> s<sup>−1</sup>, although a channel/gate insulator interface was formed by an IGZO−111 (<i>μ</i><sub>FE</sub> = ~12 cm<sup>2</sup> V<sup>−1</sup> s<sup>−1</sup>). Device simulation analysis revealed that the improvement of <i>μ</i><sub>FE</sub> in the hetero-IGZO TFTs was originated by a quantum confinement effect for electrons at the heterojunction interface owing to a formation of steep Δ<i>E</i><sub>c</sub>. Thus, we believe that heterojunction IGZO channel is an effective method to improve electrical properties of the TFTs.https://www.mdpi.com/1996-1944/13/8/1935oxide semiconductorthin-film transistorheterojunctionamorphousdevice simulationquantum confinement |
| spellingShingle | Daichi Koretomo Shuhei Hamada Yusaku Magari Mamoru Furuta Quantum Confinement Effect in Amorphous In–Ga–Zn–O Heterojunction Channels for Thin-Film Transistors Materials oxide semiconductor thin-film transistor heterojunction amorphous device simulation quantum confinement |
| title | Quantum Confinement Effect in Amorphous In–Ga–Zn–O Heterojunction Channels for Thin-Film Transistors |
| title_full | Quantum Confinement Effect in Amorphous In–Ga–Zn–O Heterojunction Channels for Thin-Film Transistors |
| title_fullStr | Quantum Confinement Effect in Amorphous In–Ga–Zn–O Heterojunction Channels for Thin-Film Transistors |
| title_full_unstemmed | Quantum Confinement Effect in Amorphous In–Ga–Zn–O Heterojunction Channels for Thin-Film Transistors |
| title_short | Quantum Confinement Effect in Amorphous In–Ga–Zn–O Heterojunction Channels for Thin-Film Transistors |
| title_sort | quantum confinement effect in amorphous in ga zn o heterojunction channels for thin film transistors |
| topic | oxide semiconductor thin-film transistor heterojunction amorphous device simulation quantum confinement |
| url | https://www.mdpi.com/1996-1944/13/8/1935 |
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