Modification of the amphoteric activity of Ge implants in GaAs by dual implantation of Ge and As

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Abstract
The electrical properties of Ge in Cr‐doped semi‐insulating GaAs implanted with both Ge and As have been studied by the van der Pauw Hall‐effect/sheet‐resistivity technique. In all cases, room‐temperature implantation of both ion species was performed sequentially at the same ion energy (120 keV) and at the same dose (ranging from 1×1013 to 3×1015/cm2). Implanted samples were annealed with pyrolytic Si3N4 encapsulants at temperatures ranging from 700 to 1000 °C. Compared with Ge single implants in GaAs, the addition of As ion implants to GaAs:Ge has been found to produce a significant enhancement of the n‐type electrical activity for ion doses of ?1×1015/cm2, a conductivity type conversion for intermediate doses, and little effect upon p‐type activity for ion doses of ?3×1013/cm2. In most cases, the electrical activation continues to increase with annealing temperature up to 1000 °C. The maximum electrical activation efficiency obtained for these dual implants was 50% at an ion dose of 1×1013/cm2 for the p‐type samples and 24% at an ion dose of 3×1014/cm2 for the n‐type samples.