Quantum interference and space charge effects in double barrier structures incorporating wide quantum wells

The current-voltage characteristics of resonant tunneling devices with well widths between 12 and 180 nm are studied. The voltage interval between the resonant peaks in the current is measured as a function of well width. For the wide wells the amplitude of the peaks in the differential conductance is modulated by an “over the barrier” interference effect involving the collector barrier. Space charge buildup and intrinsic bistability effects for a particular resonant state are found to depend critically on its energy difference from the top of the collector barrier and from lower lying standing wave states of the quantum well.