Manipulation of polarization effect to engineer III-nitride HEMTs for normally-off operation

Yung Chi Yao, Chun Ying Huang, Tai Yuan Lin, Li Lien Cheng, Ching Yun Liu, Mei Tan Wang, Jung Min Hwang, Ya Ju Lee*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

5 Citations (Scopus)


We propose a novel, normally-off AlGaN/GaN high-electron-mobility transistor (HEMT) governed by polarization engineering. The fundamental concept is to grade the Al composition of the barrier layer from GaN to AlxGa1- xN, thereby alleviating the impact of piezoelectric polarization on the two-dimensional electron gas (2-DEG) and establishing a conduction-band profile well above the Fermi energy. These effects lead to a positive shift in the threshold voltage of the device and benefit the normally-off operation. It is observed that the device's DC transfer characteristics can be further modulated simply by adjusting the Al composition of the AlyGa1- yN cap layer and the p-type doping concentration at the top of the GaN buffer layer. These findings, based on a physical simulation of the proposed device, provide a guideline for the implementation of highly efficient, normally-off AlGaN/GaN HEMTs.

Original languageEnglish
Pages (from-to)1-6
Number of pages6
JournalMicroelectronic Engineering
Publication statusPublished - 2015 Apr 20


  • 2-DEG
  • AlGaN/GaN HEMT
  • DC transfer characteristics
  • Normally-off operation
  • Polarization

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering


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