STRAIN AND MOSAIC SPREAD OF CARBON AND GALLIUM CO-IMPLANTED GAAS

The strain and crystalline perfection of GaAs implanted with either ca rbon, gallium, or both carbon and gallium ions (5 X 10(14) cm-2) were investigated using high-resolution triple axis diffractometry. We dete rmined that a significant amount of carbon occupied substitutional sit es after rapid thermal annealing only when gallium was co-implanted. T he carbon in the carbon-implanted layer remained in nonsubstitutional sites after annealing. In both cases, most of the lattice strain in th e implanted layer decreases upon annealing, but a defective crystallin e structure with an extensive mosaic spread evolves. Conventional doub le-axis x-ray measurements were employed for comparison.