Investigation of recessed gate AlGaN/GaN MIS-HEMTs with double AlGaN barrier designs toward an enhancement-mode characteristic

Tian-Li Wu*, Shun Wei Tang, Hong Jia Jiang

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

In this work, recessed gate AlGaN/GaN metal-insulator-semiconductor high-electronmobility transistors (MIS-HEMTs) with double AlGaN barrier designs are fabricated and investigated. Two different recessed depths are designed, leading to a 5 nm and a 3 nm remaining bottom AlGaN barrier under the gate region, and two different Al% (15% and 20%) in the bottom AlGaN barriers are designed. First of all, a double hump trans-conductance (gm)-gate voltage (VG) characteristic is observed in a recessed gate AlGaN/GaN MIS-HEMT with a 5 nm remaining bottom Al0.2Ga0.8N barrier under the gate region. Secondly, a physical model is proposed to explain this double channel characteristic by means of a formation of a top channel below the gate dielectric under a positive VG. Finally, the impacts of Al% content (15% and 20%) in the bottom AlGaN barrier and 5 nm/3 nm remaining bottom AlGaN barriers under the gate region are studied in detail, indicating that lowering Al% content in the bottom can increase the threshold voltage (VTH) toward an enhancement-mode characteristic.

Original languageEnglish
Article number163
JournalMicromachines
Volume11
Issue number2
DOIs
StatePublished - Feb 2020

Keywords

  • Double barrier
  • GaN
  • Metal-insulator-semiconductor high-electron-mobility transistor (MIS-HEMT)
  • Recessed gate

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