Terahertz generation in negative-effective-mass diodes

Theoretically studied current self-oscillations and spatiotemporal current patterns in quantum-well (QW) negative-effective-mass (NEM) p/sup +/pp/sup +/ diodes when the electric field is applied along the direction of the well. The origin of current self-oscillations is the formation and traveling of electric-field domains in the well. In the calculations we have accurately considered scattering contributions from carrier-impurity, carrier-acoustic phonon, and carrier-optic phonon. It is indicated that, both the applied bias and the doping concentration in the well largely influence the current patterns and self-oscillating frequencies, which lie in the THz range for the NEM p/sup +/pp/sup +/ diode having a submicrometer p-base. The NEM p/sup +/pp/sup +/ diode presented here may therefore be used as an electrically tunable THz source.