The book is meant for the introductory study in the high energy implantation in GaAs. It contains the irradiation experiment with 100 MeV, Au-197 implantation in GaAs at room temperature done at Inter University Accelerator Centre, New Delhi, India. A brief introduction to Rapid Thermal Annealing System used is given. Detailed experimental procedure of I-V characteristics of implanted samples with ohmic contacts is also mentioned. The results of annealing behavior of irradiated samples analyzed and presented using I-V data.