S-parameter based device-level C-V measurement of p-i-n single-drift IMPATT diode for millimeter-wave applications

Two different approaches of capacitance-voltage (C-V) measurement were applied to the fabricated single-drift (SD) impact-ionization avalanche transit-time (IMPATT) structures. From both the C-V results, the carrier concentrations of depleted space-charge-region (SCR) width characteristics were calculated. According to the epitaxial thickness and the doping concentration of the lightly n-doped layer, the approach applied to a 30 × 2 μm2 IMPATT device, which is based on small-signal S-parameter characterization (0.04-40 GHz), showed better agreement compared with the approach applied to a C-V structure (0.64 mm2) using the conventional low frequency (1 MHz) C-V instrument. Additionally, the E-band IMPATT operation of the 30 × 2 μm2 device has been well modelled with the capacitance value extracted from the S-parameter based C-V measurement. The good agreement between device modelling and measurement within frequency range 0.04-110 GHz shows the reliability of the small-signal S-parameter device-level C-V measurement for real mm-wave application scenarios.