Experimental Investigation of DC-RF Dispersion in AlGaN/GaN HFET’s Using Pulsed I-V and Time-Domain Waveform Measurements

Peter McGovern, Paul J. Tasker,
J.Powell*, K.P. Hilton*, J.L. Glasper*, R.S. Balmer*, t. Martin*, M.J. Uren*

Cardiff School of Engineering, Cardiff University, Cardiff, UK
Email: McGovernP@cf.ac.uk

*QinetiQLtd, Malvern, Worcestershire, UK, WR14 3PS

AlGaN/GaN HFETs have been analyzed under DC and RF Stimulus in an attempt to analyze the phenomenon of DC-RF dispersion. DC pulsed I-V measurements were performed where the pulse “off” state was set to different bias points, to simulate a class A bias condition at various drain voltages.  RF time-domain waveform measurements were also performed.  The I-V measurements exhibited the common problem of current slump, as did the RF power performance of the device.  Interestingly, it was found that there was strong correlation between the pulsed I-V and RF measurements when they are considered as a function of bias point.  Although current slump is evident during pulsed I-V measurements, it is not permanent, and there is negligible degradation of the device after prolonged RF stimulus. 

Keywords:  GaN, HEMT, HFET, DC-RF dispersion, current slump

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