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[[Vol. 78]New Diamond Transistor Exhibits High Hole Mobility_WPI-MANA.pdf](https://mdr.nims.go.jp/filesets/93e3bc39-b322-476c-a812-7d6313231cdb/download)

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International Center for Materials Nanoarchitectonics (WPI-MANA)

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[[Research Highlights Vol.78] New Diamond Transistor Exhibits High Hole Mobility](https://mdr.nims.go.jp/datasets/fc8e0e16-6f17-4eb4-aea2-dcd67be0d23a)

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2022/11/04 9:53 New Diamond Transistor Exhibits High Hole Mobility| MANAhttps://www.nims.go.jp/mana/research/highlights/vol78.html 1/2Previous  Index  NextResearch Highlights[Vol. 78]New Diamond Transistor Exhibits High Hole Mobility29 Jul, 2022A research team at WPI-MANA, using a new fabrication technique, has developed a diamondfield-effect transistor with high hole mobility, which can lead to reduced conduction loss andhigher operational speeds.Field-effect transistors (FETs) are semiconductor devices that can switch electric power and amplifyelectric signals. FETs made of wide-bandgap semiconductors can handle high power efficiently andare useful for power electronics and communications. The use of SiC and GaN is therefore growing,but diamond has a wider bandgap and more desirable properties that could boost deviceperformance.The team used a new fabrication technique to develop the FET, wherein it fabricated the transistorwith hexagonal boron nitride as a gate insulator and without exposing the diamond’s surface to air.The advantage is that it can reduce the density of negative charges on the diamond surface. If thereare negative charges, they produce random Coulomb potential, which scatters the holes when theyconduct near the diamond surface. This degrades the effectiveness of hole conduction and decreasesthe mobility of the holes.Also, with the negative charges, even if no gate voltage is applied, there are holes, and so thetransistor is "normally on," and this is not suitable for power electronics applications.https://www.nims.go.jp/mana/research/highlights/vol77.htmlhttps://www.nims.go.jp/mana/research/highlights/index.htmlhttps://www.nims.go.jp/mana/research/highlights/vol79.html2022/11/04 9:53 New Diamond Transistor Exhibits High Hole Mobility| MANAhttps://www.nims.go.jp/mana/research/highlights/vol78.html 2/2"In contrast, in our new technique, we can reduce the density of negative charges on the diamondsurface. So the holes are less scattered, and therefore we can obtain higher mobility," said teamleader Dr. Takahide Yamaguchi. "This also results in 'normally-off’ operation, which is desirable forpower electronics."Dr. Yamaguchi pointed to some possible applications of this breakthrough. "Our new approach forfabricating diamond transistors could be used to make low-loss switches for power electronics andhigh-frequency high-output amplifiers for communications."This research was conducted by Yosuke Sasama (NIMS Postdoctoral Researcher, Surface QuantumPhase Materials Group, WPI-MANA, NIMS), Takahide Yamaguchi (Principal Researcher, SurfaceQuantum Phase Materials Group, WPI-MANA, NIMS) and their collaborators.Reference“High-mobility p-channel wide-bandgap transistors based on hydrogen-terminateddiamond/hexagonal boron nitride heterostuctures”Yosuke Sasama, Takahide Yamaguchi, et al.Journal: Nature Electronics, 5, 37-44 (23 December 2021)DOI : s41928-021-00689-4AffiliationsInternational Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for MaterialsScience (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, JapanContact informationInternational Center for Materials Nanoarchitectonics(WPI-MANA)National Institute for Materials Science1-1 Namiki, Tsukuba, Ibaraki 305-0044 JapanPhone: +81-29-860-4710E-mail: mana-pr[AT]ml.nims.go.jpTo receive our e-mail newsletter “MANA Research Highlights”, please send an e-mail with "MANA ResearchHighlights request” in the subject line or main text to the following address: mana-pr_at_ml.nims.go.jp *Please change "_at_ " in the email address to @.https://samurai.nims.go.jp/profiles/sasama_yosuke?locale=enhttps://samurai.nims.go.jp/profiles/yamaguchi_takahide?locale=enhttps://samurai.nims.go.jp/profiles/sasama_yosuke?locale=enhttps://samurai.nims.go.jp/profiles/yamaguchi_takahide?locale=enhttps://www.nature.com/articles/s41928-021-00689-4