Electron states in mesa-etched one-dimensional quantum well wires

Two-dimensional, self-consistent solutions of the Schrödinger and Poisson equations are used to find the electron states in GaAs/AlGaAs quantum well wires. Both deep and shallow mesa structures are simulated. Our results show that while these structures are capable of providing the single occupied subband and wide energy separations needed for a true quantum wire, the process tolerances allowed are very small, on the order of 200 Å of width variation. Cutoff widths calculated are 1000 Å for the shallow mesa and 2100 Å for the deep mesa. The agreement with experimental results is good for the shallow mesa, but poor for the deep mesa. This suggests additional process-induced sidewall depletion mechanisms contributing to the cutoff of the deep mesa structures.