Dual implantation of Ga and Ge into GaAs

Abstract

The electrical properties of GaAs, doubly implanted with Ge+Ga, have been studied by the van der Pauw–Hall-effect/sheet-resistivity technique. In all cases both species of the dual implants were implanted sequentially at the same ion energy of 120 keV and at the same dose, with doses ranging from 1×1013 to 3×1015 cm−2. Implanted samples were annealed with pyrolytic Si3N4 encapsulants at temperatures ranging from 700 to 1000 °C. The addition for Ga ion implants to GaAs:Ge produces p-type conductivity for all doses up to an anneal temperature of 900 °C. The p-type electrical activity of Ge in GaAs:Ge+Ga was found to increase significantly over that of GaAs:Ge for doses of 3×1014 cm−2 or below, while the original n-type activity of Ge single implants was found to change to p type for doses of 1×1015 cm−2 or above, except for anneal temperatures higher than 900 °C. The maximum electrical activation efficiency obtained with the dual implantation was 61% at a dose of 1×1013 cm−2 and an anneal temperature of 950 C.