Since a few years, indium nitride promising properties for device applications have attracted much attention worldwide. Huge efforts are dedicated to optimize indium nitride growth. However, this growth is extremely challenging, in particular using the metal organic vapor phase epitaxy (MOVPE) technique which exhibits very low growth rates. This may explain why most of the samples available in the scientific community, which also present the best electrical properties, were grown by molecular beam epitaxy (MBE). However, up to date, no intrinsic indium nitride layer was obtained. InN epilayer crystalline quality suffers from the lack of lattice matched substrates, leading to the use of double‐step growth process. In this paper, we show that InN low lateral growth rate is a limiting parameter for efficient double‐step growth process. But, we also report that the use of CBrCl3 during InN growth enhances the lateral growth rate. To improve the growth rate along the c‐axis, we investigate alternative precursors for both nitrogen and indium species. We show that ammonia remains the best precursor, but combined with triethylindium, the growth rate increases with optimum crystalline quality. Finally, we compare MOVPE‐grown and MBE‐grown InN layers in order to understand the difference observed on the electrical properties. We show how thermal annealing can improve the MOVPE‐grown InN layers leading to similar electrical properties than reported in MBE‐grown samples. The role of ammonia as source of hydrogen is also discussed.

InSe is a promising material in many aspects where the role of excitons is decisive. Here we report the sequential appearance in its luminescence of the exciton, the biexciton, and the P-band of the exciton-exciton scattering while the excitation power increases. The strict energy and momentum conservation rules of the P-band are used to reexamine the exciton binding energy. The new value ≥20 meV is markedly higher than the currently accepted one (14 meV), being however well consistent with the robustness of the excitons up to room temperature. A peak controlled by the Sommerfeld factor is found near the bandgap (~1.36 eV). Our findings supported by theoretical calculations taking into account the anisotropic material parameters question the pure three-dimensional character of the exciton in InSe, assumed up to now. The refined character and parameters of the exciton are of paramount importance for the successful application of InSe in nanophotonics.

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.

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We have investigated the heteroepitaxial growth of indium nitride on sapphire substrates having different orientations. Growths were performed on C‐, A‐, M‐, and R‐plane‐oriented sapphire in order to analyze the substrate orientation effect on the structural, optical, and electronic properties of InN. The orientation relationship between InN and sapphire was deduced by θ/2θ High‐resolution X‐ray diffraction (HRXRD) measurements. These experiments show the ability to grow InN along nonpolar (1120) orientation and the semipolar (1122) orientation, depending of the orientations of the sapphire substrate. The crystalline quality was assessed by XRD symmetric and asymmetric rocking curve measurements. We observed no drastic disparity between our samples, all exhibiting a reasonable crystalline quality. Atomic force microscopy imaging on these layers revealed different surface morphologies with a roughness varying between 30 and 60 nm. Electrical properties of the InN samples were investigated by room temperature Hall effect measurements and a line shape fitting of the photoluminescence was performed in order to get optically the values of the residual carrier density in the nitride layers.

Thermal annealing of InN layers grown by metal organic vapor phase epitaxy (MOVPE) is investigated in nitrogen atmosphere for temperatures ranging from 400 to 550 degrees C and for heat treatment times up to 12 h. This treatment results in hydrogen outdiffusion, lowering significantly the residual n-type background doping. This mechanism is shown to be reversible through thermal annealing under ammonia atmosphere, responsible of hydrogen incorporation during growth. These results establish a MOVPE process allowing the obtention of InN samples, which exhibit similar electrical properties than molecular beam epitaxy grown samples: a key issue in view of future industrial production of InN based devices

Indium nitride (InN) quantum dots have been grown on gallium nitride (GaN) templates with heights of 10 and 20nm. The authors demonstrate that the surface densities of the dots are strongly affected by the nature of the carrier gas used during the growth, which can be used to modulate the surface density. The authors show here that replacing nitrogen by helium leads to a decrease of the dot surface density, while argon induces a strong increase of the density. Although validated for the InN∕GaN system, this approach has a more general scope and can be extended to other material systems.

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