High-speed InGaP/AlGaAs/InGaAs HBTs

We have fabricated high-speed InGaP/AlGaAs/InGaAs graded-base hetero-bipolar transistors (HBTs), using Mg as the base-region p-type dopant. We have obtained maximum Mg doping concentration for GaAs of 1.2/spl times/10/sup 20//cm/sup 3/. In addition, the dead region under the base metal contact layer has been etched away. With the HBT's emitter width as 1.0 um, we obtained excellent frequency characteristics of the short-circuit current-gain frequency f/sub t/ and the maximum frequency of oscillation f/sub max/ as high as approximately 130 GHz and 230 GHz, respectively. We obtained maximum toggle frequency of 22.5 GHz for a static frequency divider by using the 4-inch full process of the InGaP/AlGaAs/InGaAs graded-base HBT.