480-GHz $f_{\max}$ in InP/GaAsSb/InP DHBT With New Base Isolation $\mu$-Airbridge Design

Abstract

Self-aligned 0.55×3.5 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> emitter InP/GaAsSb/InP double heterojunction bipolar transistors demonstrating an f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> of 310 GHz and an f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> of 480 GHz are reported. Common-emitter current gain of 24, together with a breakdown voltage of 4.6 V, is measured. The devices were fabricated with a triple-mesa process and easily fabricated with a new base isolation μ-airbridge design which, moreover, significantly reduced the base-collector capacitance C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BC</sub> .