In this paper, we present the results of a study to fabricate shallow p+ n junction using Ga FIB implantation in conjunction with rapid thermal annealing (RTA). A focused 75 KeV ion beam with BO mA/cm2 current density and 0.5 μm beam diameter was used to implant Ga into (100) Si substrates at the doses from 1E13 to 5E15/cm2. The annealing temperature is from 600 °C to 1000 °C for various times, 10–30 sec. Secondary ion mass spectrometry (SIMS) and spreading resistance profiling (SRP) were used to measure the implanted Ga atomic and carrier concentration depth profiles. As compared to the conventional broad beam (BB) implantation, the FIB implanted impurity concentration depth profile has a longer tail and thus a deeper p+n junction. The damage generated by the high dose rate implantation is possibly responsible for this phenomenon. The results of SRP measurements of the FIB as-implanted samples show no Scif-anneal ing occured during implantations. p+n diodes fabricated using FIB exhibit good junction properties: ideality factor of 1.1, reverse–bias leakage current of below 5 nA/cm2 at -IV, and breakdown voltage of about 35 V.