3.8 W/mm RF Power Density for ALD Al2O3-Based Two-Dimensional Hole Gas Diamond MOSFET Operating at Saturation Velocity

Shoichiro Imanishi, Kiyotaka Horikawa, Nobutaka Oi, Satoshi Okubo, Taisuke Kageura, Atsushi Hiraiwa, Hiroshi Kawarada

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


This letter reports the small-signal and large-signal performances at high drain voltage (VDS) ranging up to 60 V for a 0.5 μ m gate length two-dimensional hole gas diamond metal-oxide-semiconductor field-effect transistor with a 100-nm-thick atomic-layer-deposited Al2O3 film on a IIa-type polycrystalline diamond substrate with (110) preferential surfaces. This diamond FET demonstrated a cutoff frequency (fT) of 31 GHz, indicating that its carrier velocity was reaching 1.0× 107 cm/s for the first time in diamond. In addition, a fT of 24 GHz was obtained at VDS=-60 V, thus giving a f T× VDS product of 1.44 THz · V. This diamond FET is promising for use as a high-frequency transistor under high voltage conditions. Under application of a high voltage, a maximum output power density of 3.8 W/mm (the highest in diamond) with an associated gain and power added efficiency were 11.6 dB and 23.1% was obtained when biased at VDS=-50 V using a load-pull system at 1 GHz.

Original languageEnglish
Article number8574928
Pages (from-to)279-282
Number of pages4
JournalIEEE Electron Device Letters
Issue number2
Publication statusPublished - 2019 Feb


  • Diamond
  • high frequency
  • high voltage
  • output power

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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