Nonlinear physics of THz sources: Duality theory in nonequilibrium nanodevice physics

There is a formal correspondence or duality in the analytical theories of self-oscillation in resonant tunneling nanostructures (RTN’s) with conventional (type-I) and with staggered (type-II) alignments of the heterostructure energy-band gaps. Two entirely difflerent physical models for type-I and type-II RTN’s were introduced and described by a unifying set of coupled nonlinear-rate equations. These coupled equations were solved for the limit cycle solution. For type-I RTN, the limit cycle predictions in the plateau agrees with experiments and simulations of AlGaAs/GaAs type I RTN. For type II RTN, the limit-cycle oscillation time-averaged results agree with the measured current-voltage (I-V) characteristic of AlGaSb/InAs/AlGaSb type-II RTN.