Mobile space-charge effects on THz-frequency characteristics and parasitic series resistance of InP IMPATT device at elevated junction temperature

Extensive simulation experiments are carried out for the first time on the feasibility of THz power generation from an InP based Double Drift Transit Time diode operating at elevated junction temperature (250°C). The effects of mobile space charge on the THz frequency performance as well as on the parasitic series resistance (R_S) of the device are also investigated by a generalized simulation scheme. The study reveals that at the optimized bias current density of 3.2 × 10⁸ Am^-2, the device is capable of delivering output power density of 3 × 10⁹ Wm^-2 with an efficiency of 7%. With the increasing bias current density the space charge effects are found to become prominent and this causes serious degradation of THz performances of the device as far as output power density, efficiency and negative resistivity profiles are concerned. It is observed that at a high bias current density of 7 × 10⁸ Am^-2, space charge increases the value of R_S significantly (~38%). These optimized simulation data may be suitably used for fabrication of InP -IMPATT device at 0.3 THz region for application in high-power THz module.