On-Wafer GaAs Schottky Diode Characterization Using an Integrated Pulse I-V/Pulse S-Parameter Measurement System

An automated on-wafer pulsed I-V pulsed S-parameter measurement system capable of synchronous voltage, current, and S-parameter sampling during 500-ns pulsed bias excursions has been demonstrated. Data obtained with this measurement system illustrate its utility for characterizing the relationships between Schottky diode quiescent bias conditions, rectifying barrier potential and C-V slope. These relationships result from deep levels in GaAs (traps) that affect the conduction processes of active devices. At microwave frequencies, the applied fields vary more rapidly than the time constants associated with traps: thus, carriers in deep levels do not contribute to the microwave properties of the device. Conventional bias-dependent S-parameter characterization used for nonlinear diode and field-effect transistor (FET) model development does not account for these effects. However, the measurement system described herein does account for these effects by coupling the applied quiescent bias with short, low-duty-factor, pulsed-bias excursions.