Indium nitride was grown on Al2O3 substrate and characterized by x-ray diffraction, Raman, electrical resistivity, Hall, and magnetoresistance studies. Thermoelectric and electrical properties of free-standing films were measured in situ under high pressure HP cycling to 20 GPa, across a phase transformation to a rock-salt-structured lattice. HP-cycling-induced amorphization was established. The thermopower Seebeck effect data evidence that both crystalline and amorphous InN kept n-type conductivity to 20 GPa. Pressure effect on the carrier concentration and effective mass is analyzed. Two features that can be related to structural transitions in amorphous InN were found near 11 and 17 GPa.

We compare the quality factor values of the whispery gallery modes of microdisks incorporating GaN quantum dots (QDs) grown on AlN and AlGaN barriers by performing room temperature photoluminescence (PL) spectroscopy. The PL measurements show a large number of high Q factor (Q) resonant modes on the whole spectrum which allows us to identify the different radial mode families and to compare them with simulations. We report a considerable improvement of the Q factor which reflect the etching quality and the relatively low cavity loss by inserting QDs into the cavity. GaN/AlN QDs based microdisks show very high Q values (Q > 7000) whereas the Q factor is only up to 2000 in microdisks embedding QDs grown on AlGaN barrier layer. We attribute this difference to the lower absorption below bandgap for AlN barrier layers at the energies of our experimental investigation.

Nonpolar (11-20) (Ga,In)N multi-quantum wells have been studied by polarized, temperature dependent photoluminescence (PL). A non monotonic temperature dependence of the difference in PL peak energies recorded for E parallel to c or E perpendicular to c, and of the polarization ratio is observed. We interpret these effects by first an orthorhombic distortion of the crystal and an increased electron-hole exchange energy relative to GaN. This increase is in agreement with calculations on the effect of confinement on the exciton exchange splitting.

We report the growth of indium nitride on AlPO4, which is a piezoelectric substrate, by using metal organic vapor phase epitaxy (MOVPE). The substrate we used was the as-grown (011) surface of an AlPO4 crystal grown by hydrothermal synthesis. InN growth occurs as the nonpolar M-plane. The structural, optical, and electrical properties of the epilayer are comparable with those of layers obtained by conventional growth on polar GaN MOVPE templates deposited on C-plane sapphire. We discuss the utilization of other MX-O-4 oxides for growing nitrides.

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.

We report the experimental determination of the interband deformation potentials of indium nitride by combining both optical spectroscopy investigations and high-resolution X-ray measurements performed on a series of InN films grown by metal organic vapour-phase epitaxy. Our approach, which follows the one used for GaN by Shan et al. [Phys. Rev. B. 54 (1996) 13460], gives here for InN a1=-7.66 eV, a2=-2.59 eV, b1=5.06 eV, and b2=-2.53 eV.

We have performed a detailed investigation of the photoluminescence features taken at 2 K on a series of GaxIn1-xN alloys grown by metal-organic vapour-phase epitaxy through the whole composition range. The evolution of the photoluminescence lineshape of GaInN alloys in the indium-rich region is dominated by doping effects rather than by band-gap tailing effects correlated to existence of random chemical crystal inhomogeneities. The lineshape of the photoluminescence indicates a residual electron concentration of about 1018–1019cm-3 in the bulk part of the epilayers. The value we get for the bowing parameter is b=2.8 eV.