MEASURING, MODELING, AND MINIMIZING CAPACITANCES IN HETEROJUNCTION BIPOLAR-TRANSISTORS

We demonstrate methods to separate junction and pad capacitances from on-wafer S-parameter measurements of HBTs with different areas and lay outs. The measured junction capacitances are in good agreement with mo dels, indicating that large-area devices are suitable for monitoring v endor epi-wafer doping. Measuring open HBTs does not give the correct pad capacitances. Finally, a capacitance comparison for a variety of l ayouts shows that bar-devices consistently give smaller base-collector values than multiple dot HBTs. Copyright (C) 1996 Elsevier Science Lt d.