Multi-stage annealing of defects in ion-implanted double-barrier diodes

The d.c. and a.c. characteristics of double-barrier diodes have been used to probe the large-scale annealing of defects within ion-implanted GaAs. Multi-stage annealing of defects was elucidated by the staged recovery of resonant tunnelling through ion-implanted diodes. Surprisingly, the current - voltage characteristics of some ion-implanted diodes after very rapid anneals were qualitatively identical to the as-grown characteristics, but the peak-current density was two orders of magnitude lower. This is explained by the creation of small percolation paths of as-grown material during the initial stages of annealing, where these paths surrounded clusters of defects. A simple capacitance model based on the creation of these percolation paths is described, and is consistent with the capacitance - voltage data. The idea that small-area percolation paths of as-grown material were created within the ion-implanted DBDs during very rapid annealing was supported by the observation of very-low bias resonant tunnelling and single-electron switching at 4.2 K. Both these phenomena are usually observed only within small-area pristine DBDs.