Photo effect based avalanche multiplication measurement in highly scaled SiGe HBTs

A new photo effect based technique for measuring the avalanche multiplication factor (M - 1) is proposed. The technique enables M - 1 measurement at high operating current densities required for high speed operation, where conventional techniques fail because of self-heating. Using the proposed technique, M - 1 was measured up to 24 mA//spl mu/m/sup 2/ on SiGe HBTs featuring 120 GHz peak f/sub T/. Implications for circuit applications are also discussed.