We report on the electrodeposition of ZnO with different surface morphologies. We demonstrate by three different ways that morphology is ruled by the growth rate, and therefore strongly influences the optical properties of the layers. Whereas small size well-connected grains are obtained at high growth rate, the crystals evolve toward large disoriented nanorods since the kinetic of the reaction is hindered. The corresponding RMS roughnesses ranges from 35nm to 119nm, resulting in diffusion of the light from far UV to visible-wavelength. The surface morphology is shown to be directly mastered by electrochemical parameters which enable either a 2D or 3D growth mechanism.

CdS thin films were grown on different substrates (glass, GaAs, Si, Al2O3) by CBD. The rms roughness of the CdS layers, measured on AFM pictures, ranges from 11 to 95 nm depending on the chemical nature of the substrate Thermal annealing of the samples leads to an improvement of the CdS crystalline quality with a conversion from cubic to hexagonal phase, whatever substrate is used, as assessed by XRD. Thermal annealing also improves the optical properties. While as-grown CdS layers photoluminescence is due to defect related emission around 1.7eV, annealed samples show dominant near band edge photoluminescence emission around 2.4 e V.

Using the electron emission channeling and Rutherford backscattering/channeling techniques, the influence of the mosaicity of a thin film on the axial channeling of charged particles was investigated. It is found that crystal mosaicity leads to a broadening and a degradation of the experimental channeling effects. This phenomenon, which is shown to be of major importance when assessing the lattice site of impurities in a single crystal, can be modeled quantitatively by using the mosaic tilt and twist components derived from X-ray rocking curve scans. As a case study, we illustrate that our approach allows to accurately determine the lattice site of Er in AlN, despite the significant influence of mosaicity on the channeling measurements.

CuInSe2 (CIS) layers were grown by co-evaporation in a molecular beam epitaxy system onto soda lime glass substrates by using both two-step and three step processes. The physical properties of the layers were investigated using X-ray diffraction (XRD) and optical spectroscopy. The sample atomic composition was assessed by energy dispersive analysis of X-rays. Cu-rich or In-rich CIS thin films were obtained exhibiting strong preferential (112) and (220)/(204) orientations in both cases. We performed thermal annealing at 450 °C under nitrogen, keeping Se overpressure to avoid Se desorption from the layer. The annealed layers all exhibit improved crystalline quality, with reduced stoichiometric discrepancy. The secondary phases like CuxSe1 − x or InxSe1 − x are no more observable by XRD measurements. Regarding the preferential orientation, thermal annealing of Cu-rich CIS layers favours the (112) orientation leading to a more (112) textured layer after annealing, whatever the initial preferential growth orientation was. In opposite, thermal annealing of In-rich samples increases the (220)/(204) texture of the sample.

We present a study of non-intentionally doped InN epilayers directly grown on sapphire substrate by metal organic chemical vapour deposition (MOCVD) technique. Structural and optical characterisations of this sample have been conducted by SEM, temperature-dependent photoluminescence and time resolved pump-probe techniques. Triangular-shaped structures of InN are observed to grow above hexagonal-shaped columnar structures as seen from the SEM image. Photoluminescence spectra reveal a peak energy of 0.75 eV, supporting the existence of the narrow bandgap of InN. So far, various papers in the literature quote the carrier lifetime in InN epilayers grown on sapphire substrate in the presence of a buffer layer such as GaN. Herein, we report carrier lifetime measurements conducted on InN epilayer deposited directly on sapphire substrate, in the absence of GaN as a buffer layer.

In this work, we present a comprehensive study on the hydrogen impurity depth profiles in InN films with polar c-plane and nonpolar a-plane surface orientations in relation to their structural and free-electron properties. We find that the as-grown nonpolar films exhibit generally higher bulk and near-surface H concentrations compared to the polar InN counter-parts. The latter may be partly associated with a change in the growth mode from 2D to 3D and a decrease in the grain size. Thermal annealing leads to a reduction of H concentrations and the intrinsic H levels are influenced by the structural characteristics of the films. The factors allowing reduction of bulk H and free electron concentrations in a-plane films are discussed. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim