The natural aging process of InN nanostructures by the formation of indium oxides is examined by transmission electron microscopy related techniques. Uncapped and GaN-capped InN quantum dots (QDs) on GaN/sapphire substrates were grown under the same conditions and kept at room temperature/pressure conditions. The GaN capping layer is found to preserve the InN QDs in the wurtzite phase, avoiding the formation of group-III oxides, while in the uncapped sample, a thin layer of cubic phases are formed that envelops the nucleus of wurtzite InN. These cubic phases are shown to be mainly bcc-In2O3 for long aged samples where the nitrogen atoms in the InN surface layers have been substituted by atmospheric oxygen. This process implies the gradual transformation of the In sublattice from hcp to a quasi-fcc structure. Metastable zinc-blende InN phases rich in oxygen atoms are proposed to act as intermediate phases and they are evinced in samples less aged. The large concurrence of interplanar spaces, the twin formation, and the existence of a free surface that facilitates the transformation support this mechanism and would explain the high instability of the InN nanostructures at ambient conditions

We extend to any temperature, the sophisticated calculation of the evolution of the 2 K photoluminescence energy of InN proposed by Arnaudov et al. [Phys. Rev. B 69, 115216 (2004)], in view of determining the residual doping of thin films. From the detailed line shape modeling, we extract the full width at half maximum of the photoluminescence line which, in the first order, varies like n0.51 at low temperature. This allows us to propose a handy tool for rapid residual doping evaluation. Last, temperature and inhomogeneous broadening effects are analyzed. Ignoring the latter is shown to lead to an overestimation of the residual doping.

Since a few years, a lot of research efforts have been devoted to InN, the least known of the semiconducting group-III nitrides. Most of the samples available today have been grown using the molecular beam epitaxy technique, and fewer using the metal organic vapor phase epitaxy (MOVPE) method. Whatever the method, the growth of InN is extremely challenging, in particular due to the fact that no lattice matched substrate is available. This paper present results on the improvement of the InN crystal quality in MOVPE. In particular, the use of carbon halides to enhance the lateral growth is demonstrated, leading to extremely smooth InN surfaces. A new process for the realization of InN nanostructures by recrystallization is presented, which allows to obtain a better crystal quality than direct MOVPE growth

: We report the growth of indium-rich InGaN alloys by metal-organic vapour phase epitaxy, using ammonia, trimethylgallium and trimethylindium as precursors. Compared to indium nitride, our alloy samples present substantial photoluminescence robustness with temperature. The analysis of the optical properties of these samples versus temperature indicates the existence of two non radiative recombination channels: one with a thermal activation temperature of 77 K and another one with an activation temperature ranging from 300 K for InN up to 640 K for In0.72Ga0.28N. The latter competes with the former at low temperatures whilst the former rules the optical properties at ambient conditions