Normally-off gate-recessed AlGaN/GaN-on-Si hybrid MOS-HFET with Al 2O3 gate dielectric

A. L. Corrion, M. Chen, Rongming Chu, S. D. Burnham, S. Khalil, D. Zehnder, B. Hughes, K. Boutros

Research output: Chapter in Book/Report/Conference proceedingConference contribution

9 Scopus citations


GaN-based HFETs offer a combination of high breakdown field, high current densities, and low on-resistance, making them well-suited for power-switching applications. Normally-off FETs are preferred in power switching applications for circuit simplicity and safety. Recently, a new type of normally-off GaN device has been reported: the hybrid metal-oxide-semiconductor (MOS)- or metal-insulator-semiconductor (MIS)-HFET, consisting of an MOS-type structure under the gate for normally-off operation and an HFET-like structure in the access regions for low on-resistance [1-6]. Optimization of the insulator-epi interface and insulator quality is critical for this type of device, since the electrons under gate electrode are in direct contact with the gate insulator. Previous reports of hybrid MOS-HFETs used SiO2 or SiN gate dielectrics deposited by plasma-enhanced chemical vapor deposition (PECVD). However, alternative deposition methods such as atomic layer deposition (ALD) have been shown to result in superior thickness control, uniformity, conformality, and film quality, while ALD high-k gate dielectrics such as Al2O3 have generated significant interest for GaN HFETs due to excellent GaN interface quality. In this work, we fabricated normally-off AlGaN/GaN hybrid MOS-HFETs on (111) Si substrates using gate recess etching combined with an ALD Al2O3 gate dielectric for low gate leakage, low on-resistance, and high breakdown voltage. The gate fabrication process was optimized to reduce the trap density associated with the dielectric and eliminate threshold voltage hysteresis, which can result from slow traps in the dielectric or at the dielectric-epi interface [7]. A three-terminal breakdown voltage (VB) of 1370V was measured at a gate bias of 0 V on a device with a 20 mm gate periphery and a low specific on-resistance (R on) of 9.0 m-cm2. The resulting VB 2/Ron figure of merit of 208 MW/cm2 is among the highest values reported to-date for normally-off GaN-on-Si HFETs.

Original languageEnglish (US)
Title of host publication69th Device Research Conference, DRC 2011 - Conference Digest
Number of pages2
StatePublished - Dec 1 2011
Event69th Device Research Conference, DRC 2011 - Santa Barbara, CA, United States
Duration: Jun 20 2011Jun 22 2011

Publication series

NameDevice Research Conference - Conference Digest, DRC
ISSN (Print)1548-3770


Other69th Device Research Conference, DRC 2011
Country/TerritoryUnited States
CitySanta Barbara, CA

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering


Dive into the research topics of 'Normally-off gate-recessed AlGaN/GaN-on-Si hybrid MOS-HFET with Al 2O3 gate dielectric'. Together they form a unique fingerprint.

Cite this