Design of InP Segmented-collector DHBTs with Reduced Collector Transit Time τc for Large Power Bandwidth Power Amplifiers

• Published in: 2018 76th Device Research Conference (DRC) pp. 1 - 2
• Main Authors: Fang, Yihao, Sculley, Jonathan P., Urteaga, Miguel E, Carter, Andy D, Yoder, Paul D., Rodwell, Mark J.W.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.06.2018
• DOI: 10.1109/DRC.2018.8442142
• ISBN: 9781538630273; 1538630273

InP double-heterojunction bipolar transistors (DHBTs) have demonstrated power gain cutoff frequencies (f_{max}) above 1THz under low collector voltage due to electron velocity overshoot in the InP drift collector [1] [2]. Under higher collector voltage, however, a quick onset of \Gamma-\mathrm{L} scattering limits the average electron velocity to the saturation velocity (Fig. 1(a)-(c)), leading to a Johnson's figure-of-merit (JFOM) second to GaN HEMTs and a limited transistor power bandwidth for InP DHBTs [3]. Here we propose a velocity-engineered device structure called the segmented-collector DHBT (SC-DHBT) that incorporates p-type scattering layers within the drift collector to reduce the electron kinetic energy and force a greater electron distribution into the low effective mass \Gamma- valley for extended velocity overshoot (Fig. 3(a)). Transport simulations show the collector transit time \tau_{c} is reduced from 1.23ps in the reference design to 0.90ps in a double scatterer design at V_{cb}=5\mathrm{V}, J_{c}{=} 1mA/um 2 . The proposed SC-DHBT design is suited for large power bandwidth power amplifiers.