Effect of reservoir-electron motion on the frequency response of double-barrier resonant tunneling

The frequency response of the double-barrier resonant-tunneling current to the bias-voltage modulation is studied theoretically taking into account the effect of the dynamic motion of reservoir electrons in the contacts. A density-matrix approach with a transfer Hamiltonian is used and the incoherent scatterings in the contacts are modeled with damping constants. It is shown that the bandwidth of the device is determined not only by the electron-transfer rates through the barriers but also by the phase-smearing rates for the tunneling electrons. It is also shown that the frequency response of the tunneling current exhibits resonance enhancements in the high-frequency region. The enhancements are attributed to the quantum oscillations of the electrons between the quantum well and contact regions.