DocumentCode :
992809
Title :
A physics-based frequency dispersion model of GaN MESFETs
Author :
Islam, Syed S. ; Anwar, A.F.M. ; Webster, Richard T.
Author_Institution :
Electr. Eng. Dept., Rochester Inst. of Technol., NY, USA
Volume :
51
Issue :
6
fYear :
2004
fDate :
6/1/2004 12:00:00 AM
Firstpage :
846
Lastpage :
853
Abstract :
A physics-based model for GaN MESFETs is developed to determine the frequency dispersion of output resistance and transconductance due to traps. The equivalent circuit parameters are obtained by considering the physical mechanisms for current collapse and the associated trap dynamics. Detrapping time extracted from drain-lag measurements are 1.55 and 58.42 s indicating trap levels at 0.69 and 0.79 eV, respectively. The dispersion frequency is in the range of megahertz at elevated temperature, where a typical GaN power device may operate, although at room temperature it may be few hertz. For a 1.5 × 150 μm GaN MESFET with drain and gate biases of 10 V and -1 V, respectively, 5% decrease in transconductance and 62% decrease in output resistance at radio frequencies (RFs) from their DC values are observed. The dispersion characteristics are found to be bias dependent. A significant decrease in transconductance is observed when the device operates in the region where detrapping is significant. As gate bias approaches toward cutoff, the difference between output resistance at dc and that at RF increases. For drain and gate biases of 10 and -5 V, output resistance decreases from 60.2 kΩ at dc to 7.5 kΩ at RF for a 1.5 μm × 150 GaN MESFET.
Keywords :
III-V semiconductors; equivalent circuits; gallium compounds; power MESFET; semiconductor device models; wide band gap semiconductors; 0.69 eV; 0.79 eV; 1.55 s; 10 V; 58.42 s; GaN; GaN MESFET; GaN power device; current collapse; detrapping time; equivalent circuit parameters; frequency dispersion; output resistance; radio frequencies; transconductance; Electrical resistance measurement; FETs; Gallium nitride; HEMTs; MESFETs; MODFETs; Radio frequency; Temperature distribution; Time measurement; Transconductance; Current collapse; GaN MESFET; detrapping time; frequency dispersion;
fLanguage :
English
Journal_Title :
Electron Devices, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9383
Type :
jour
DOI :
10.1109/TED.2004.829620
Filename :
1300815
Link To Document :
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