Three-dimensional self-consistent simulation of interface and dopant disorders in delta-doped grid-gate quantum-dot devices

We study the influence of interface roughness and dopant disorder on the electronic and charging properties of a δ-doped Al1−xGaxAs/GaAs quantum-dot grid-gate device by computer simulation. The analysis is performed for a device unit cell at T=4.2 K by self-consistent adiabatic one-dimensional (1D) Schrödinger and 3D Poisson’s simulation, within the local density approximation. Random boundary conditions that accounts for cell-to-cell influence of disorder is considered as well. The random effect of interface roughness produces very short-ranged potential distortions over distances of the order of a monolayer, resulting in a maximum deviation of 20% in the charging energy. Sensitivity analysis of the device to both random fluctuations in the number and positioning of the dopant ions shows that dopant number variations from device to device can result in fluctuations in the charging energy of as much as 50% per dopant. Isolated acceptor point charges in the quantum well change the modes of electron confinement, giving rise to fluctuations in the charging energy of the order of 25%.