Theoretical study of terahertz current oscillation in GaAs1-xNx

We have theoretically investigated current self-oscillation in doped n(+)nn(+) GaAs1-xNx diodes driven by direct current (dc) electric field. The current self-oscillation is associated with negative differential velocity effect in the highly nonparabolic conduction band of this unique material system. By solving a time-dependent drift-diffusion model that takes into account the negative differential velocity effect, we provide a detailed analysis of the current oscillations. The frequencies of current oscillations are in the gigahertz to terahertz region, depending on the doping concentration and the applied dc electric field. The calculated average current density is in qualitative agreement with the measured result. (c) 2008 American Institute of Physics.