S-parameter characterization and lumped-element modelling of millimeter-wave single-drift impact-ionization avalanche transit-time diode

Five silicon (Si) p++-n−-n++ samples were grown at various doping concentrations (1.0 × 1017-2.2 × 1017 cm−3) in an n− layer by using the reduced-pressure CVD technique. By using these samples, 30 × 2 µm2 single-drift (SD) impact-ionization avalanche transit-time (IMPATT) diodes were processed with Si-based monolithic millimeter-wave integrated circuit (SIMMWIC) technology.1,2) The samples within a small process window exhibited a large negative differential resistance at approximately the avalanche frequency, as confirmed by small-signal S-parameter characterization. A model based on depletion width was given to explain the conditions for the appearance of the negative differential IMPATT resistance, which is the basis of millimeter-wave amplifier and oscillator applications. Furthermore, a measurement-based small-signal lumped-element model was established to describe the IMPATT functionality from the circuit component aspect. This lumped-element model shows a negative differential resistance within a well-defined range in the given element parameters, which can explain the experimental observations.