Does the quantity of bulk trapping, due to hot carrier injection, increase with increased Vgd at e.g. Vds=10V in AlGaN/GaN HEMTs?
I understand that with increased Vgd at Vds=10V that there would be increased electric field. This should increase bulk trapping as there is greater electron energy provided by the electric field, correct? Are there any references to show this?
Are there any references to suggest that bulk trapping does not increase with increased Vgd and e.g. Vds=10V?
Increased Vgd does result in creating more interface traps, bulk traps in buffer layer. I do not know whether bulk traps will keep increasing as you keep stressing with higher Vgd but surely interface traps will be generated at a faster rate and these are fast responding traps that interact more strongly with carrier kinetics and device performance. I am attaching two papers which discuss trap generation with hot carrier stressing by sustained high Vgd value.
Sincerely,
Dr. Nabil Shovon Ashraf.
Yes, you can expect carrier trapping in the bulk to increase because as you say the kinetic energy of the carriers increases with an increase in Vgd. However, this may depend on whether it is the gate or the drain that is kept static. Please see the following papers:
1. Detailed analysis of DC-RF Dispersion in AlGaN/GaN HFETs using Waveform Measurements [DOI: 10.1109/EMICC.2006.282745 ]
2. Buffer Trap related knee walkout and the effects of self-heating in AlGaN/GaN HEMTs [DOI: 10.1149/2.0021711jss]
It is clear that at static gate bias conditions, increasing the Vgd would increase the dispersion at the knee of the output characteristics while the experiment shows that the opposite is the case when the drain bias is kept static. Although the results shown are based on RF amplifier operation where you would expect trapping to play a significant role, I would expect similar results for a DC stressed device.
Thank you very much for the recommendation Brendan. This is very helpful!
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