AlN/GaN Metal Insulator Semiconductor Field Effect Transistor on Sapphire Substrate

Sanghyun SEO  Kaustav GHOSE  Guang Yuan ZHAO  Dimitris PAVLIDIS  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E91-C   No.7   pp.994-1000
Publication Date: 2008/07/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.7.994
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Heterostructure Microelectronics with TWHM 2007)
Category: Nitride-based Devices
Keyword: 
AlN,  MISFETs,  HFETs,  Drift-diffusion simulations,  

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Summary: 
AlN/GaN Metal Insulator Semiconductor Field Effect Transistors (MISFETs) were designed, simulated and fabricated. DC, S-parameter and power measurements were also performed. Drift-diffusion simulations using DESSIS compared AlN/GaN MISFETs and Al32Ga68N/GaN Heterostructure FETs (HFETs) with the same geometries. The simulation results show the advantages of AlN/GaN MISFETs in terms of higher saturation current, lower gate leakage and higher transconductance than AlGaN/GaN HFETs. First results from fabricated AlN/GaN devices with 1 µm gate length and 200 µm gate width showed a maximum drain current density of 380 mA/mm and a peak extrinsic transconductance of 85 mS/mm. S-parameter measurements showed that current-gain cutoff frequency (fT) and maximum oscillation frequency (fmax) were 5.85 GHz and 10.57 GHz, respectively. Power characteristics were measured at 2 GHz and showed output power density of 850 mW/mm with 23.8% PAE at VDS = 15 V. To the authors knowledge this is the first report of a systematic study of AlN/GaN MISFETs addressing their physical modeling and experimental high-frequency characteristics including the power performance.