InP/GaAsSb DHBTs With 500-GHz Maximum Oscillation Frequency

Abstract

We report the realization of 0.3-μm emitter InP/GaAsSb/InP DHBTs with cutoff frequencies <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> = 365 GHz and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MAX</sub> = 501 GHz. Our devices were implemented with a 15-nm C-doped graded base and a 125-nm InP collector and feature a peak current gain β = 35, with a base sheet resistance <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SH</sub> = 1160 Ω/sq. The present transistors are the first InP/GaAsSb DHBTs to feature <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MAX</sub> = 500 GHz, according to three extraction schemes. The present transistor performance is limited by an undepleted collector layer associated with a doping tail extending from the subcollector.