The effect of the defective nature of the substrate on the alloying behaviour of Xe implanted Au(55 ran)/n-GaAs system was studied using cross sectional transmission electron microscopy.
Low dose Xe implantation (700 keV, 1*1014 ions/cm2) caused the formation of about SO nm thick polycrystalline region of GaAs beneath the gold layer. Annealing the implanted sample at 450°C gold diffused through the polycrystalline GaAs region and formed large pits of Au(Ga) solid solution in the defective area of GaAs having stacking faults and twins. The formation of a regrown GaAs covering layer was observed on the top of the reacted metallization simultaneously.
High dose implantation of Xe++ ions resulted in the formation of amorphous GaAs layer with a thickness of about 750 nm. Twinned regions of GaAs were observed at the amorphous - crystalline GaAs interface by high resolution electron microscopy. Ion beam caused phase transition was observed in this sample. The amorphous GaAs region recrystallized to single crystalline GaAs due to annealing at 400°C.