AN ASSESSMENT OF POTENTIAL NONLINEAR CIRCUIT MODELS FOR THE CHARACTERIZATION OF RESONANT-TUNNELING DIODES

The intrinsically fast process of resonant tunneling through double ba rrier heterostructures along with the existence of negative differenti al resistance in the current-voltage characteristic of these structure s has led to their implementation as sources for high frequency electr omagnetic energy. While sources based upon resonant tunneling diodes ( RTD's) have produced frequency of oscillations up to 712 GHz, only mic rowatt levels of performance has been achieved above 100 GHz, Since st ability criteria play a critical role in determining the deliverable p ower of any oscillator, a physically accurate equivalent-circuit model for the RTD is extremely important for optimizing the dynamics of the device-cavity package, This study identifies a distinctly new equival ent circuit model for characterizing the modes of oscillation in RTD-b ased sources. Specifically, in order to exhibit the fundamental seif-o scillations and the overall IV characteristics (plateau structure and hysteresis) observed experimentally, an accurate circuit model of the RTD must incorporate; (i) a quantum-wed inductance which directly chok es the nonlinear conductance and, (ii) a nonlinear access resistance, associated with the accumulation of charge in the injection region of the double barriers, with a nonlocal dependence on the bias across the double barrier structure.