C–Si bonded two-dimensional hole gas diamond MOSFET with normally-off operation and wide temperature range stability

Te Bi*, Yuhao Chang, Wenxi Fei, Masayuki Iwataki, Aoi Morishita, Yu Fu, Naoya Niikura, Hiroshi Kawarada

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


A C–Si bonded SiO2/diamond interface is formed under a SiO2 mask during the selective diamond growth at a high temperature in a H2 atmosphere including methane (5%). A few monolayers with C–Si bonding at the SiO2/diamond surface are confirmed through X-ray photoelectron spectroscopy at the C1s and Si2p core levels from 290 eV to 271 eV and 107 eV–95 eV, respectively. In addition, secondary ion mass spectroscopy results suggest that the C–Si bonds, and not C–H bonds, are majority at the interface and are mainly responsible for the field effect transistor (FET) operation. Two-dimensional hole gas C–Si diamond metal–oxide–semiconductor FET (MOSFETs) are fabricated using the C–Si diamond sub-surface as a p-channel. The MOSFETs in which the actual length from the source to the drain (LSD) is 12 μm–6 μm show appreciable field-effect mobility (e.g. 140 cm2V−1s−1 at LSD = 12 μm and 300 K) and normally-off operation. The wide temperature characteristics of the C–Si MOSFETs are confirmed and the device shows high stability, and a high on/off ratio of 106 is maintained at 673 K. The C–Si bonding at the SiO2/diamond interface provide a lower interface state density which makes the MOSFET show high drain current density and field-effect mobility with normally-off operation.

Original languageEnglish
Pages (from-to)525-533
Number of pages9
Publication statusPublished - 2021 Apr 30


  • Carbon electronics
  • C–Si Diamond surface
  • Diamond
  • Metal–oxide–semiconductor field-effect transistor (MOSFET)
  • Two-dimensional hole gas (2DHG)

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)


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