Monolithically Integrated Enhancement-Mode and Depletion-Mode β-Ga2O3 MESFETs with Graphene-Gate Architectures and Their Logic Applications

Janghyuk Kim, Jihyun Kim

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)


Ultrawide band gap (UWBG) β-Ga2O3 is a promising material for next-generation power electronic devices. An enhancement-mode (E-mode) device is essential for designing power conversion systems with simplified circuitry and minimal loss. The integration of an E-mode field-effect transistor (FET) with a depletion-mode (D-mode) FET can build a high-performance logic circuit. In this study, we first demonstrated the realization of an E-mode quasi-two-dimensional (quasi-2D) β-Ga2O3 FET with a novel graphene gate architecture via a van der Waals heterojunction. Then, we monolithically integrated it with a D-mode quasi-2D β-Ga2O3 FET, achieving an area-efficient logic circuit. The threshold voltage of the n-channel UWBG β-Ga2O3 material was controlled by forming a novel architecture of a double-gate graphene/β-Ga2O3 heterojunction, where both graphene and β-Ga2O3 were obtained by a mechanical exfoliation method. The fabricated double graphene-gate β-Ga2O3 metal-semiconductor FET (MESFET) was operated in the E-mode with a positive threshold voltage of +0.25 V, which is approximately 1.2 V higher than that of a single-gate D-mode β-Ga2O3 MESFET. Both E-/D-modes β-Ga2O3 MESFETs showed excellent electrical characteristics with a subthreshold swing of 68.9 and 84.6 mV/dec, respectively, and a high on/off current ratio of approximately 107. A β-Ga2O3 logic inverter composed of E-/D-mode β-Ga2O3 devices exhibited desired inversion characteristics. The monolithic integration of an E-/D-mode quasi-2D FET with an UWBG channel layer can pave the way for various applications in smart and robust power (nano) electronics.

Original languageEnglish
Pages (from-to)7310-7316
Number of pages7
JournalACS Applied Materials and Interfaces
Issue number6
Publication statusPublished - 2020 Feb 12

Bibliographical note

Funding Information:
This research was supported by the National Research Foundation of Korea (2017M1A3A3A02015033 and 2018R1D1A1A09083917).

Publisher Copyright:
Copyright © 2020 American Chemical Society.


  • depletion-mode FET
  • enhancement-mode FET
  • gallium oxide
  • two-dimensional material
  • ultrawide band gap

ASJC Scopus subject areas

  • General Materials Science


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