COMPLETE P-TYPE ACTIVATION IN VERTICAL-GRADIENT FREEZE GAAS CO-IMPLANTED WITH GALLIUM AND CARBON

High-resolution triple-axis x-ray diffractometry and Hall-effect measu rements were used to characterize damage evolution and electrical acti vation in gallium arsenide co-implanted with gallium and carbon ions. Complete p-type activation of GaAs co-implanted with 5x10(14) Ga cm(-2 ) and 5x10(14) C cm(-2) was achieved after rapid thermal annealing at 1100 degrees C for 10 s. X-ray diffuse scattering was found to increas e after rapid thermal annealing at 600-900 degrees C due to the aggreg ation of implantation-induced point defects. In this annealing range, there was similar to 10%-72% activation. After annealing at higher ann ealing temperatures, the diffuse scattered intensity decreased drastic ally; samples that had been annealed at 1000 degrees C (80% activated) and 1100 degrees C (similar to 100% activated) exhibited reciprocal s pace maps that were indicative of high crystallinity. The hole mobilit y was about 60 cm(2)/V s for all samples annealed at 800 degrees C and above, indicating that the crystal perfection influences dopant activ ation more strongly than it influences mobility. Since the high-temper ature annealing simultaneously increases dopant activation and reduces x-ray diffuse scattering, we conclude that point defect complexes whi ch form at lower annealing temperatures are responsible for both the d iffuse scatter and the reduced activation. (C) 1996 American Institute of Physics.