Study On THz Radiation And Photo-carriers Transportation Characteristics By Means Of Monte Carlo Simulation

In this paper, the generation, detection and characteristics of THz wave are introduced, and the THz time domain spectrum detecting, THz imaging and application in the biology and information technology are presented as well. Much especially, the simulation process of GaAs PCSS's via Monte Carlo is showed, including the energy model and the scattering model, then some scattering mechanism that should be considered is brought forward. The flow chart and program structure are presented, mainly focusing on carriers' initialization, free flight, Poisson's Equation and scattering mode and etc. Through the generation and motion of carriers inside the GaAs PCSS's, the NDA property is under discussed, and more, the NDA curve and occupation ratio of electrics in the satellite valley is obtained, that the causation of overshoot of carriers is indicated as well. Based on these, the influence of bias electric field, width of laser pulses and density of carriers on THz wave's near- and far-field is studied, and then the ways to improve THz radiation is presented. According to the relationship between space-charge field and bias field, the movement rule and distribution of carriers are discussed, and the influence of carriers distribution on the field inside the device and the output current wave are also expanded. It is indicated in the simulation that when the bias field intensity is higher than 3500 V/cm and space-charge field is large enough, the electrics forms two clusters. Moreover, the space-charge field perpendicular to the bias field is discussed elementarily.