Electrical activation and carrier compensation in si and mg implanted GaN by Scanning Capacitance Microscopy

We studied the effect of the annealing temperatures (in the 1100-1200 degrees C temperature range) on the electrical activation of ion implanted Si and Mg in GaN. Si+ ions were implanted at multiple energies (from 80keV to 180keV) and with a total fluence up to 2.7x 10(14) cm(-2) in heteroepitaxial GaN films on sapphire. Some samples were subjected to conventional low ramp rate processes at 1100 degrees C and 1200 degrees C in N-2 ambient. A fast ramp rate pre-annealing in N-2 ambient was carried out on other samples before those low-ramp rate processes at 1100 degrees C and 1200 degrees C. The calibrated Scanning Capacitance Microscopy (SCM) was applied to determine the active ('i.e. substitutional) Si depth profile. The rapid pre-annealing process leads to an increase from 36% to 63% in the substitutional Si dose. The Mg ions were implanted with energy of 50keV and fluence of 5x10(14) cm(-2) in n GaN layer on sapphire. Two fast ramp rate annealing process were performed. However, only an annealing at 1200 degrees C for 30s in N-2 allows to observe, by means of SCM, the formation of a p layer.