In this work, coalescence aspects of wurtzite-III-nitride epitaxy are addressed. The coalescence phenomena have been studied in thin epilayers by means of electron and atomic force microscopies, and electron and x-ray diffractions. This study generalizes the growth parameters responsible for the rapid coalescence of III-nitride films, and describes the coalescence qualitatively and, partly, analytically for the case of heteroepitaxy in nonequilibrium conditions. Coalescence time and the corresponding diffusion coefficients at elevated temperatures were estimated for GaN and InN depositions. The rate of coalescence has been found to impact on the structure and morphology of III-nitride epilayers. A simple growth model was suggested to explain the formation of domain boundaries and ͑0001͒ stacking faults formed during the coalescence. In particular, it is shown that two adjacent and tilted, hexagonal-shaped 2H domains may form a noncoherent boundary explicitly along a ͕11 ¯00͖ plane. We also suggest that the interaction between tilted domains induces the localized lateral growth of the most epitaxially oriented domain forming a basal ͑0001͒ stacking fault followed by the formation of surface macrosteps, and consequently the termination of a threading dislocation by its dissociation and propagation under the formed ͑0001͒ stacking fault.

The chemical and electron transport properties of oxidized indium nitride epilayers and indium oxide/indium nitride heterostructures are reported. It is shown that the accumulation of electrons at the InN surface can be manipulated by the formation of a thin surface oxide layer using an ozone-assisted oxidation processing. It results in improved transport properties and in a reduction of the electron sheet concentration of the InN epilayer caused by a passivation of the surface donors and a shift of the electron density distribution peak from the surface toward the bulk InN. Using the ensemble Monte Carlo simulation method, the electron mobility for different dislocation densities and surface band bending values has been calculated. The theoretical results correlate well with our experimental data. In opposition to the ozone treatment, in epitaxial oxide/nitride heterojunctions the electron sheet concentration of InN raises due to the increasing band bending at the heterointerface affecting adversely the electron transport properties.

The structural, chemical and electron transport properties of In2O3/InN heterostructures and oxidized InN epilayers are reported. It is shown that the accumulation of electrons at the InN surface can be manipulated by the formation of a thin surface oxide layer. The epitaxial In2O3/InN heterojunctions show an increase in the electron concentration due to the increasing band banding at the heterointerface. The oxidation of InN results in improved transport properties and in a reduction of the sheet carrier concentration of the InN epilayer very likely caused by a passivation of surface donors. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Cubic (c‐) InN is predicted to possess superior electronic properties for device applications, while c‐In2O3 is an excellent candidate as gate material for InN based high‐frequency field effect transistors. In this paper, the epitaxial growth of the InN/In2O3 and In2O3/InN heterosystems was investigated. High‐quality c‐InN (001) was deposited on (001) In2O3 tem‐ plate, while single crystalline c‐In2O3 was epitaxially grown on hexagonal InN (0001). The epitaxial relationship of the heterosystems was determined. Phenomenological models of the nucleation and of an atomic arrangement at the interface are proposed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The concept of a standing wave (SW) interferometer has been extensively investigated for the last decade. A key problem within these efforts is the development of a transparent ultra‐thin photodetector for sampling the intensity profile of the generated SW. We report on the simulation and fabrication as well as on the structural and optoelectronical characterization of highly transparent AlGaN/GaN double‐heterostructure and InGaN metal–semiconductor–metal photodetectors based on intraband and band‐to‐band transitions, respectively. Both detectors have a 20 nm thick optically active layer designed for the light absorption at the wavelength of ∼633 nm. Besides good structural properties of both Al0.35Ga0.65N/GaN and In0.56Ga0.44N structures, the absorbance of the InGaN‐based detector was found ∼20 times higher compared to the AlGaN/GaN photodetectors. The temporal characteristics of the detectors are limited by both the RC‐constant and by the persistent photocurrent effect. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)