Capacitance–voltage characteristics and switching time of double barrier resonant tunneling diode fabricated with epi-Si and γ-Al2O3

Capacitance-voltage and conductance-voltage characteristics of resonant tunneling diodes fabricated with epitaxial Si/γ-Al2O3 heterostructure have been studied at room temperature. The capacitance-voltage characteristics of this structure show a large capacitance peak near the resonant tunneling bias. This capacitance peak is considered as quantum capacitance originated from the charge storage in the quantum well of the structure during tunneling process. Capacitance-voltage characteristics also were studied at different frequencies to understand the charge storage mechanism in the resonant tunneling diode structure. Resonant tunneling diodes with different barrier thicknesses were studied and tremendous improvement in the NDR characteristics was observed. A maximum peak-to-valley current ratio of 248 was obtained at room temperature. Using this capacitance value switching time and maximum operational frequency of the RTD structure were determined.