论文部分内容阅读
Terahertz(THz) technology can be used in information science,biology,medicine,astronomy,and environmental science.THz sources are the key devices in THz applications.The author gives a brief review of THz semiconductor sources,such as GaAs_(1-x)N_x Gunn-like diodes,quantum wells(QWs) negative-effective-mass (NEM) THz oscillators,and the THz quantum cascade lasers(QCLs).THz current self-oscillation in doped GaAs_(1-x)N_x diodes driven by a DC electric field was investigated.The current self-oscillation is associated with the negative differential velocity effect in the highly nonparabolic conduction band of this unique material system. The current self-oscillations and spatiotemporal current patterns in QW NEM p~+pp~+ diodes was studied by considering scattering contributions from impurities,acoustic phonons,and optic phonons.It is indicated that both the applied bias and the doping concentration strongly influence the patterns and self-oscillating frequencies.The NEM p~+pp~+ diode may be used as an electrically tunable THz source.Meanwhile,by using the Monte Carlo method, the device parameters of resonant-phonon THz QCLs were optimized.The results show that the calculated gain is more sensitive to the injection barrier width,the doping concentration,and the phonon extraction level separation, which is consistent with the experiments.
Terahertz (THz) technology can be used in information science, biology, medicine, astronomy, and environmental science. THz sources are the key devices in THz applications. The author gives a brief review of THz semiconductor sources, such as GaAs_ (1-x ) N_x Gunn-like diodes, quantum wells (QWs) negative-effective-mass (NEM) THz oscillators, and THz quantum cascade lasers (QCLs) .THz current self-oscillation in doped GaAs_ (1-x) a DC electric field was investigated. The current self-oscillation is associated with the negative differential velocity effect in the highly nonparabolic conduction band of this unique material system. The current self-oscillations and spatiotemporal current patterns in QW NEM p ~ + pp ~ + diodes was studied by considering scattering contributions from impurities, acoustic phonons, and optic phonons. It is indicated that both both applied bias and the doping concentration strongly influence the patterns and self-oscillating frequencies. NEM p ~ + pp ~ + diode may be used as an electrically tunable THz source.Meanwhile, by using the Monte Carlo method, the device parameters of resonant-phonon THz QCLs were optimized. The results show that the calculated gain is more sensitive to the injection barrier width, the doping concentration, and the phonon extraction level separation, which is consistent with the experiments.