Mg–Ga liquid metal ion source for implantation doping of GaN

Abstract

A magnesium liquid metal ion source was investigated for p-type doping of GaN. The metal is an alloy composed of 33.3% Mg and 66.7% Ga. The source type is a direct heating needle source with a spring-type reservoir, which is constructed using tungsten wire and a ceramic tube. The source has been tested and characterized in a NanoFab 150 focused ion beam (FIB) system. A typical source lifetime was 250 μA h. Mg+ ion implantation of GaN thin films has been performed at different energies between 30 and 100 keV for doses ranging from 5×1013 to 1×1015 cm−2. After Mg+ FIB implantation, samples were annealed at 1100 °C in N2 ambient. Low temperature photoluminescence with a He–Cd laser of 325 nm exhibited the donor—acceptor recombination peak, which was enhanced by the activated magnesium ions.