Electrical activation and carrier compensation in Si and Mg implanted GaN by Scanning Capacitance Microscopy

摘要

We studied the effect of the annealing temperatures (in the 1100-1200°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 2.7 × 10~(14) cm~(-2) in heteroepitaxial GaN films on sapphire. Some samples were subjected to conventional low ramp rate processes at 1100°C and 1200°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°C and 1200°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 5 ×10~(14) cm~(-2) in n" GaN layer on sapphire. Two fast ramp rate annealing process were performed. However, only an annealing at 1200°C for 30s in N_2 allows to observe, by means of SCM, the formation of a p layer.