Multistable Charge Build-Up and a New Switching Principle in Coherent-Electron Tunneling Devices

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Abstract
A new mechanism leading to multiple stable operating states in coherent-electron tunneling devices is proposed and numerically verified in a model system. This mechanism utilizes the charge accumulation in virtually bound and quasi-bound states in a quantum-well/barrier structure. The electrostatic energy associated with these states causes the lowest occupied of them to be pinned to the conduction-band edge. For fixed bias, more than one solution to the Poisson equation is found, with each solution being uniquely determined by the quantum number of the pinned state. These different solutions show up as different current branches in the I(V) characteristic of a tunneling diode. Switching between them – for example by using lateral gates – should be very fast, as virtually bound states have a much shorter life time than quasi-bound states.