Transient thermal processing is employed for implant activation, contact alloying, implant isolation and dehydrogenation during III-nitride device fabrication. We have compared use of InN, AlN and GaN powder as methods for providing a N2 overpressure within a graphite susceptor for high temperature annealing of GaN, InN, A1N and InAlN. The AlN powder provides adequate surface protection to temperatures of ∼1100°C for AlN, > 1050°C for GaN, ∼600°C for InN and ∼800°C for the ternary alloy. While the InN powder provides a higher N2 partial pressure than AlN powder, at temperatures above ∼750°C the evaporation of In is sufficiently high to produce condensation of In droplets on the surfaces of the annealed samples. GaN powder achieved better surface protection than the other two cases.