InGaAs/AlAs/InGaAsP resonant tunneling bipolar transistors grown by chemical beam epitaxy

Resonant tunneling bipolar transistors (RTBT's) have been systematically studied using chemical beam epitaxy (CBE) for the first time. The RTBT structure studied is a InP-based transistor, consisting of single or multiple AlAs/In/sub 0.75/Ga/sub 0.25/As/AlAs RTD's in the emitter layer of a conventional heterojunction bipolar transistor (HBT) and an InGaAs or InGaAsP collector layer. Using the InGaAsP collector layer, the RTBT showed an improvement of breakdown voltage from 4 V to 10 V. The averaged DC /spl beta/'s are around 10 and 20 at 300 K and 77 K, respectively. In the transfer I-V characteristics, the RTBT showed 1 to 4 negative differential transconductance (NDT) peaks with peak-to-valley current ratios of 1.5 to 5.28 at 300 K. Using such NDT peaks, several RTBT digital functions were demonstrated at room temperature, including a frequency multiplier and exclusive NOR gate.<
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