Effects of punch-through on Terahertz frequency characteristics of 4H-SiC based p++ p n n++ IMPATT devices

Simulation investigations on 4H-SiC based double-drift avalanche-transit-time diode clearly establishes it´s potential at higher terahertz region. Further, the effects of punch-through on the terahertz behavior of the device are studied for the first time, through a generalized simulation technique. The computed results revealed that for a fixed bias current density, when the space-charge effect is not prominent, the optimum negative conductance decreases whereas corresponding frequency for highest negative conductance increases with the increase of punch-through, determined by doping density and the thickness of the active layer of the device. Decrease of punch-through factor leads to an increase of device negative-resistance and efficiency. The results may be used for design optimization of SiC THz IMPATT oscillators for application in THz communication systems.