Capacitances in double-barrier tunneling structures

Capacitances in a double-barrier tunneling structure are calculated for the specific sequential electron tunneling regime. Starting from Luryi´s (1988) definition of quantum capacitance, the authors model the charge accumulation in the well during the tunneling process using the Fermi-Dirac distribution. Analytical formulas for the total capacitance and conductance are derived. A complete small-signal model is proposed that demonstrates the external capacitance and conductance of the structure and its frequency behavior. The authors show both theoretically and experimentally that the capacitance in a tunneling structure is both bias- and frequency-dependent