RBS AND RECOIL SPECTROMETRY ANALYSIS OF COSI2 FORMATION ON GAAS

Mass and energy-dispersive recoil spectrometry has recently reached th e state of development where it is possible to separately characterise Ga and As in GaAs samples. Since it is possible to simultaneously cha racterise several elements (light as well as heavy), e.g. C, O, Si, Co , Ga and As, the technique is suited for examining the depth distribut ion of metallisation contacts on GaAs. In a Swedish-Australian collabo ration a recoil detector telescope was attached to a beamline of the F N tandem accelerator ''ANTARES'', at Lucas Heights Research Laboratori es, Australia. In the measurements presented here, I-127(10)+ at an en ergy of 77 MeV was employed to analyse GaAs samples with thin film ove rlayers - Si(220 nm)/Co(50 nm)/[100]-GaAs. A reference sample and samp les annealed at 300 to 600-degrees-C were analysed. The measurements s howed that CoSi2 is formed during annealing at and above 500-degrees-C with no detectable reaction between the GaAs-substrate and the CoSi2 overlayer.