Ion implanted cathode doping notches in GaAs Gunn material

The fabrication of cathode doping notches in GaAs Gunn material by use of ion implantation has been investigated. Two techniques were studied: Epitaxial GaAs having an n⁺-n-n²⁺ structure was implanted with either p-type dopant, magnetium ions, or compensating oxygen ions. Alternatively Gunn material, without an n⁺ contact layer, was implanted with both n-type dopant selenium ions and p-type magnesium ions to form the cathode-notch configuration. In both cases annealing was carried out in an arsenic vapour overpressure. It is found that the magnitude of notches produced is governed by the extent to which impurity diffusion takes place during post-implant annealing.