Influence of SiC hetero-polytype barriers on the performance of IMPATT terahertz diodes

Abstract

The SiC hetero-polytypes with perfect interfaces and no diffusion pollution are adopted to innovatively design the impact ionization avalanche transit-time (IMPATT) diodes. The performance of DC, large-signal and noise of the proposed diodes operating at the atmospheric low-loss window frequency 0.85 THz are estimated via numerically solving the fundamental device equations with and without quantum correction incorporated the tunnel and density-gradient of carriers. The influence from SiC hetero-polytype barriers and material properties on the performance of IMPATT diodes is analyzed. The advantages in power, efficiency and noise generating in the diodes of 4H/6H–SiC hetero-polytypes can be due to high critical breakdown electric field strength and weak ionizing in 4H–SiC and 6H–SiC. However, small power and heavy noise emerging from the devices of 3C/4H–SiC and 3C/6H–SiC hetero-polytypes can be owing to low critical breakdown electric field strength and strong ionizing in 3C–SiC. The noise electric field peaks arising from the strong ionizing layers while deviating from the interfaces in hetero-polytypes are illustrated. The evident quantum effect on the diodes without 3C–SiC while the slight effect on the devices included 3C–SiC are attributed to low-barriers embedded in the former diodes while high-barriers involved in the latter devices, respectively. • The SiC hetero-polytypes are employed to design the impact ionization avalanche transit-time diodes (IMPATTDs). • The 4H/6H-SiC hetero-polytype IMPATTDs imply advantages in power, efficiency and noise due to weak ionizing in materials. • The noise electric field peaks arise from the strong ionizing layers while deviate from the in hetero-interfaces. • The IMPATTDs with 3C/4H-SiC and 3C/6H-SiC hetero-polytype high-barriers encounter weak quantum effect.