An analytic model for the barrier-limited mode of operation of the permeable base transistor

The Permeable Base Transistor (PBT) is a novel semiconductor device structure employing a metal control electrode embedded in a single crystal of semiconductor. Over much of the operating range of the PBT the current density is limited by the energy barrier in the vicinity of the control electrode, An analytic description of this mode of operation is presented. The microscopic electrostatic potential within the device is calculated within the depletion-layer approximation. The electrostatic potential determines the height and shape of the energy barrier, which in turn determines the current density. Transport over the barrier is studied, with both dissipative mechanisms (described by the diffusion equation) and ballistic mechanisms (thermionic emission) taken into account.