Impurity-Induced Breakdown in GaAs with Partially Ordered Si-Doping

Abstract

The static and dynamic current-voltage behaviour including the temperature and magnetic field dependence are investigated in GaAs with dopants arranged in parallel monoatomic planes (δ-doping). The S-shaped I-V characterictics of such partially ordered structures are compared with homogeneously doped samples of the same effective concentration and compensation ratio. The dopant concentrations are below the metal-insulator transition, and the ground states and first excited states are still well seperated from the conduction band edge. The δ-doped samples show a lower critical breakdown field and a shorter branch with negative differential conductivity. The current densities remain higher in the post breakdown region, too, as long as impurity scattering is dominant. Significant differences with respect to oscillations and hysteresis loops are not found. Time resolved measurements allow to distinguish the times for initiation, filamentation and evolution at higher fields.