Does velocity overshoot reduce collector delay time in AlGaAs/GaAs HBTs?
- 1 June 1991
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Electron Device Letters
- Vol. 12 (6) , 335-337
- https://doi.org/10.1109/55.82079
Abstract
The effect of velocity overshoot on the collector delay in an AlGaAs/GaAs heterojunction bipolar transistor (HBT) is examined. A new impulse response technique to rigorously evaluate the total transit-time delay using transient Monte-Carlo simulation is introduced. By applying the technique to a conventional HBT and comparing the result with a similar calculation ignoring the effects of velocity overshoot, it is found that velocity overshoot effects are difficult to observe in the normal operating range of base-collector bias. Impulse response analysis predicts that velocity overshoot should reduce the collector delay in AlGaAs/GaAs HBTs but the effect should rapidly diminish with increasing bias. It is also shown that impulse response is sensitive to the field profile. Intentional, unintentional, or current-induced variations in the collector field profile may have substantial effects on collector delay.<>Keywords
This publication has 6 references indexed in Scilit:
- Collector signal delay in the presence of velocity overshootIEEE Electron Device Letters, 1990
- Influence of electron velocity overshoot on collector transit times of HBTsIEEE Transactions on Electron Devices, 1990
- Monte Carlo study of the influence of collector region velocity overshoot on the high-frequency performance of AlGaAs/GaAs heterojunction bipolar transistorsIEEE Transactions on Electron Devices, 1988
- A possible near-ballistic collection in an AlGaAs/GaAs HBT with a modified collector structureIEEE Transactions on Electron Devices, 1988
- Electron velocity overshoot in the collector depletion layer of AlGaAs/GaAs HBT'sIEEE Electron Device Letters, 1986
- A proposed structure for collector transit-time reduction in AlGaAs/GaAs bipolar transistorsIEEE Electron Device Letters, 1986