Thermal evolution of small N-D complexes in deuterated dilute nitrides revealed by in-situ high resolution X-ray diffraction

In this article we studied the thermal evolution of nitrogen-deuterium (N-D) complexes which form in dilute nitride GaAs1-x N-x alloys as a consequence of D irradiation. These complexes are particularly important and interesting because they lead to the electronic passivation of N and also because their formation is accompanied by a strain reversal (from tensile to compressive) of the as-grown material. By collecting in-situ high resolution X-ray diffraction rocking-curves during thermal annealing, we were able to monitor in real time the evolution of the lattice parameter (a) of the samples, demonstrating that two processes are involved in the dissolution of N-D clusters. During the first process a evolves from values larger than that of the GaAs substrate saturating at values very close to the GaAs one, while the second process, that starts at a higher temperature, leads to an almost complete recovery of the D-free GaAs1-x N-x lattice parameter. By analizing the thermal evolution of a, we were able to extract information about the energetics of the two N-D complexes dissolution steps.