Conductance fluctuations in a double-barrier resonant tunneling device

Abstract

We have investigated conductance fluctuations due to tunneling through impurity states in the quantum well of a double-barrier resonant tunneling device. The impurity states are donor-related and are associated with a low-density Si \ensuremath{\delta}-doping layer incorporated into the center plane of the quantum well. At constant temperature, the relative amplitude of the conductance fluctuations is determined by the absolute number of donor impurities in the well and is found to scale as $({\mathrm{SN}}_{d}{)}^{\ensuremath{-}1/2},$ where ${N}_{d}$ is the areal density of donor atoms in the well, and S is the area of the device. The typical voltage period of the fluctuations is determined by the larger of kT or the natural linewidth of the state. There is excellent quantitative agreement between the experimental results and an existing theoretical model for conductance fluctuations in this type of system.