Short-Channel Effect Limitations on High-Frequency Operation of AlGaN/GaN HEMTs for T-Gate Devices
- 24 September 2007
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Electron Devices
- Vol. 54 (10), 2589-2597
- https://doi.org/10.1109/ted.2007.904476
Abstract
AlGaN/GaN high-electron mobility transistors (HEMTs) were fabricated on SiC substrates with epitaxial layers grown by multiple suppliers and methods. Devices with gate lengths varying from 0.50 to 0.09 mum were fabricated on each sample. We demonstrate the impact of varying the gate lengths and show that the unity current gain frequency response (fT) is limited by short-channel effects for all samples measured. We present an empirically based physical model that can predict the expected extrinsic fT for many combinations of gate length and commonly used barrier layer thickness (tbar) on silicon nitride passivated T-gated AlGaN/GaN HEMTs. The result is that even typical high-aspect-ratio (gate length to barrier thickness) devices show device performance limitations due to short-channel effects. We present the design tradeoffs and show the parameter space required to achieve optimal frequency performance for GaN technology. These design rules differ from the traditional GaAs technology by requiring a significantly higher aspect ratio to mitigate the short-channel effects.Keywords
This publication has 39 references indexed in Scilit:
- Gate-Length Dependence of DC Characteristics in Submicron-Gate AlGaN/GaN High Electron Mobility TransistorsJapanese Journal of Applied Physics, 2007
- Bulk GaN and AlGaN∕GaN heterostructure drift velocity measurements and comparison to theoretical modelsJournal of Applied Physics, 2005
- Measurements of Unity Gain Cutoff Frequency and Saturation Velocity of a GaN HEMT TransistorIEEE Transactions on Electron Devices, 2005
- Intrinsic Transit Delay and Effective Electron Velocity of AlGaN/GaN High Electron Mobility TransistorsJapanese Journal of Applied Physics, 2005
- Physics of GaN-based heterostructure field effect transistorsPublished by Institute of Electrical and Electronics Engineers (IEEE) ,2005
- High performance 0.25 μm gate-length AlGaN/GaN HEMTs on sapphire with power density of over 4.5 W/mm at 20 GHzSolid-State Electronics, 2003
- 2.1 A∕mm current density AlGaN∕GaN HEMTElectronics Letters, 2003
- Monte Carlo calculation of two-dimensional electron dynamics in GaN–AlGaN heterostructuresJournal of Applied Physics, 2002
- Evaluation of effective electron velocity in AlGaN/GaN HEMTsElectronics Letters, 2000
- DC and microwave performance of high-current AlGaN/GaN heterostructure field effect transistors grown on p-type SiC substratesIEEE Electron Device Letters, 1998