Study On Effect Of Photo-illumination On Si/SiC Asymetrical Superlatice Avalanche Transit Time Device: A High Power Terahertz Room Temperature Source

Abstract

The paper deals with comparative study and analysis of Si/4H-SiC asymmetrically doped superlattice based Avalanche Transit time (ATT) device, operating at Terahertz frequency region, under normal and photo-illuminated conditions. A generalised non-linear quantum drift diffusion model is developed for the analysis. The simulation study reveals that due to the superlattice structure, the device is capable of generating a considerable amount of power density (~2.7x1011 Wm-2) at 0.5 THz with an efficiency of ~ 46%, at 50% voltage modulation under normal (unilluminated) condition. Whereas, under photo-illumination, keeping the amount of percentage modulation fixed, significant change in output power density and efficiency, due to the effect of additional photo-generated charge-carriers, are found. The authors have made the analysis realistic by incorporating the temperature dependent carrier ionization rate, saturation drift velocity, mobility and effective mass along with enhanced leakage current effect due to photon absorption. To the best of authors’ knowledge, this is the first report on non-linear optical analysis of Si/4H-SiC superlattice ATT device at higher Terahertz region.