Observation of a large capacitive current in a double barrier resonant tunneling diode at resonance

Capacitance-voltage measurements of double barrier In0.53Ga0.47As/AlAs resonant tunneling diodes show a large capacitance peak at a bias near resonance. The measured peak capacitance is about five times larger than the calculated depletion capacitance. This large capacitance is interpreted as the capacitance between the emitter and the quantum well, which is activated near resonance only when the quantum well has a sufficient number of electrons to screen the ac electric field. An equivalent circuit with the new added series RC component is proposed and the effect on the high frequency operation of a resonant tunneling diode is discussed.