Asymmetric Double-barrier Structures Research Articles

Incoherent resonant tunneling without reflection in asymmetric double-barrier structures

The scattering processes inside the quantum well, which destroy the coherency of the wave function of the electron in a double-barrier resonant tunneling structure, are modeled by an imaginary scattering potential. The reflection coefficient, which is nonzero for an asymmetric structure without the imaginary potential, becomes zero at the resonance energy of the structure having an imaginary potential of a particular magnitude. The dependence of this particular magnitude of the imaginary potential on the ratio of the thicknesses of the two barriers is examined. For a structure in which one of the barriers is infinitely wide, this particular magnitude of the imaginary potential is equal to the width of the resonance of the structure without the imaginary potential.

Photocreated holes and their effect on the luminescence, space charge and resonant tunnelling current in double barrier structures

The resonant tunnelling of photocreated holes in a double barrier structure, which was specially designed for spectroscopic studies, is investigated using photoluminescence. The effect of photocreated holes on the resonant tunnelling current, space charge build-up in the quantum well and the photoluminescence spectrum in an asymmetric double barrier structure as a function of excitation intensity is studied.

Space-charge effects and ac response of resonant tunneling double-barrier diodes

We analyse theoretically the small-signal ac response of a resonant tunneling double-barrier semiconductor diode using the sequential tunneling approach. Electrostatic feedback effects due to space charge buildup in the quantum well are included in the analysis. The results are expressed in terms of an equivalent circuit which is used to interpret measurements of the capacitance of an asymmetric double-barrier structure at low frequencies (< 1 MHz). The frequency dependence of the real and imaginary parts of the impedance at microwave frequencies are also discussed.