Hall effect and Raman analysis of residual damage and free electron concentration in Si-implanted GaAs: a quest for better doping efficiency

The implantation-induced initial damage was determined by Rutherford backscattering, whereas the amount of residual damage present in the samples after thermal annealing was estimated by Raman spectroscopy. Additionally, scattering by LO phonon-plasmon coupled modes was used to study the properties of the free electron gas in the implanted layer, including its depth distribution. Free carrier concentrations deduced from the analysis of the plasmon modes agree with the Hall-effect results. Multi-energy implantation in combination with higher implant temperature is suggested as a way to increase doping efficiency by reducing high local concentrations and lessen the probability of compensating defects formation.