Abstract
In this paper, the relationship between the terahertz radiation and the spatial distribution of photogenerated carriers under different bias electric field is studied. Terahertz pulses and the photocurrent of SI-GaAs photoconductive antenna are measured by the terahertz time-domain spectroscopy system. The occupancy rate for photogenerated carriers for different energy valleys is obtained by comparing the photocurrent of terahertz field integrating with respect to time with the photocurrent measured by oscilloscope. Results indicate that 93.04% of all photogenerated carriers are located in the Γ valley when the bias electric field is 3.33 kV/cm, and 68.6% of all photogenerated carriers are transferred to the satellite valley when the bias electric field is 20.00 kV/cm. With the bias electric field increasing, the carrier occupancy rate for the satellite valley tends to saturate at 72.16%. In order to obtain the carrier occupancy rate for the satellite valley and saturate value at the high bias electric field, an ensemble Monte Carlo simulation based on the theory of photo-activated charge domain is developed.
Highlights
Terahertz (THz) radiation is generated by using various techniques such as ultrafast photoconductive antennas [1,2,3,4], rectification of optical pulses, second order nonlinear optical effect [5,6], quantum-cascade lasers [7], and coupled double quantum-well structure’s carrier oscillations [8,9].Using of photoconductive antennas is one of the most common sources of THz radiation due to its high intensity efficiency and large bandwidth
Carlo simulation based on the theory of photothe high bias electric field, an ensemble Monte Carlo simulation based on the theory of photo-activated activated charge domain (PACD) isConsidering developed.the
The occupancy rate of photogenerated carriers for different energy valleys is measured by comparing the photocurrent of terahertz field integrating with respect to time with the measured by comparing the photocurrent of terahertz field integrating with respect to time with the photocurrent measured by oscilloscope
Summary
Terahertz (THz) radiation is generated by using various techniques such as ultrafast photoconductive antennas [1,2,3,4], rectification of optical pulses, second order nonlinear optical effect [5,6], quantum-cascade lasers [7], and coupled double quantum-well structure’s carrier oscillations [8,9]. Under certain external conditions such terahertz radiation (such as radiant power, frequency, waveform and spatial distribution) generated asby triggering and determined bias electricby field, characteristics terahertz radiation The relationship between the photocurrent and has focused on the inter-valley scattering of photogenerated carriers with the increasing of bias electric terahertz wave radiation caused by the carriers’ inter-valley scattering of SI-GaAs PCA is not studied field [15].experiment. In order to obtain the terahertz radiation and characteristics of the photoconductive the carriers’ the inter-valley scattering of SI-GaAs. PCA is notradiation studied inand the experiment. The properties of multi-energy valley scattering carriers in a SI-GaAs PCA are investigated It provides a theoretical basis for generating high power terahertz radiation using GaAs PCA’s nonlinear working mode.
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