Equivalent circuit and capacitance of double barrier resonant tunneling diode

By measuring the scattering parameters (S parameters) with on-wafer probing techniques, the small signal impedances of double barrier resonant tunneling diodes up to 18 GHz have been obtained. The high-frequency impedance found can be successfully reproduced by a parallel R-C circuit along with a series R-L circuit. Our study indicates that the double barrier quantum well structure can be represented by the parallel R-C circuit alone, while the inductance results from the air-bridge lines to the probe contacts. The capacitance-voltage (C-V) relationship is also obtained. Well-defined structures corresponding to the tunneling effect are found. An increase in capacitance after tunneling is found in the C-V curve, and it is attributed to the charge accumulation at the quasibounded state within the quantum well.