Temperature and bias investigation of self heating effect and threshold voltage shift in pHEMT's
✍ Scribed by M. Alvaro; A. Caddemi; G. Crupi; N. Donato
- Publisher
- Elsevier Science
- Year
- 2005
- Tongue
- English
- Weight
- 209 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0026-2692
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✦ Synopsis
In the present work we analyze the performance of power pseudomorphic HEMT's having scaled gate widths (300, 600, 900 mm) under a wide range of bias and temperature conditions to investigate the onset of an hot electron regime. These devices exhibit a negative slope of I D with respect to V DS and a subsequent negative differential resistance under high power dissipation conditions. This reduction in the drain current can be explained by a degradation of the carrier velocity in the two dimensional electron gas due to the self-heating effect.
The output IKV characteristics of our devices are also affected by the threshold voltage shift. It results that the threshold voltage increases linearly by decreasing the temperature. This threshold voltage shift causes a decrease of the transconductance when the devices is biased closer to the pinch-off. Consequently, the forward transmission parameter S 21 at microwaves shows a degradation at lower temperatures despite the fact that the transport properties improve upon cooling.