Abstract
In this work, the effects of emitter ledging on DC and RF performance in sub-micron InP DHBTs are investigated. We have demonstrated that incorporating a 160-nm emitter ledge leads to an over 100% increase in DC current gain (β), rising from 16 to 34. This gain increase is primarily due to the suppression of emitter peripheral surface recombination. However, increased emitter ledge also leads to a reduction in device high frequency fT and fMAX performance due to increase in device transit time and extrinsic resistance. Trade-off between enhanced beta gain and degraded RF bandwidth needs to be further studied on the emitter ledge length.
