Influence of On-Wafer Parasitic Effects on Mason's Gain of Down-Scaled InP HBTs

The determination of Mason’s gain is associated with various problems for down-scaled millimeter-wave and sub-THz transistors, which compromises the reliability of the extracted maximum frequency of oscillation. In this work, we investigate the influence of on-wafer parasitic effects introduced by neighboring structures and probes on Mason’s gain. A full-wave 3D electromagnetic simulation environment is applied for this purpose. Furthermore, a fabricated down-scaled InP HBT with 300nm emitter width is considered. The simulated and measured raw scattering parameters for the 300nm InP HBT are corrected by applying an 8-term error model of the calibration technique. The systematic analysis of on-wafer parasitic effects reveals that the parasitic probe-to-probe coupling, even it is weak, is a source of peculiarities in Mason’s gain in case of 8-term correction, whereas the influence of the neighboring structures remains negligible.