SIMULATION OF QUANTUM TRANSPORT IN MEMORY-SWITCHING DOUBLE-BARRIER QUANTUM-WELL DIODES

Recent experiments on GaAs/AlAs double-barrier diodes incorporating n( -)/n(+)/n(-) spacer layers have shown that they exhibit two conduction curves that remain distinct across zero bias. Such devices can be rev ersibly switched between the two conduction curves and retain memory o f the curve last switched to, even after short-circuit conditions. In this paper, we model the memory-switching phenomenon using a quantum k inetic formulation based on the Wigner distribution function. To obtai n accurate Wigner distribution functions, an improved four-point diffe rence scheme with an upwind bias is used to model the drift term in th e equation of motion. The calculations result in two equilibrium (zero -voltage) states in double-barrier diodes incorporating n(-)/n(+)/n(-) spacer layers. Associated with each equilibrium state is a distinct a nd stable conduction curve. This work is a step toward an understandin g of the more complex aspects of the phenomenon, such as state switchi ng when the device is driven far from equilibrium.