Field-domain dynamics in negative-effective-mass terahertz oscillators

Abstract

We have theoretically studied electric-field-domain dynamics and current self-oscillations in dc-biased negative-effective-mass (NEM) p + pp + diodes. The formation and traveling of electric-field domains in the diodes are investigated in detail with a realistic treatment of the scatterings contributions from carrier-impurity, carrier-acoustic phonon, and carrier-optic phonon within the balance-equation theory. The interesting patterns of the spatiotemporal electric-field domains are shown as a gray density plot with the applied bias as a controlling parameter. It is found that, the applied bias could largely influence the current patterns and self-oscillating frequencies, which lie in the THz range for the NEM p + pp + diode with a submicrometer p-base. The NEM p + pp + diode may therefore be developed as an electrically tunable THz-frequency oscillator.