We report on metal-organic vapor phase epitaxial growth of (112¯2) InN on (112¯2) GaN templates on m-plane (101¯0) sapphire substrates. The in-plane relationship of the (112¯2) InN samples is [1¯1¯23]InN||[0001]sapphire and [11¯00]InN||[12¯10]sapphire, replicating the in-plane relationship of the (112¯2) GaN templates. The surface of the (112¯2) InN samples and the (112¯2) GaN templates shows an undulation along [11¯00]InN,GaN, which is attributed to anisotropic diffusion of indium/gallium atoms on the (112¯2) surfaces. The growth rate of the (112¯2) InN layers was 3-4 times lower compared to c-plane (0001) InN. High resolution transmission electron microscopy showed a relaxed interface between the (112¯2) InN layers and the (112¯2) GaN templates, consistent with x-ray diffraction results. Basal plane stacking faults were found in the (112¯2) GaN templates but they were terminated at the InN/(112¯2) GaN interface due to the presence of misfit dislocations along the entire InN/GaN interface. The misfit dislocations were contributed to the fully relaxation and the tilts of the (112¯2) InN layers. X-ray photoelectron spectroscopy was used to determine the polarity of the grown (112¯2) InN sample, indicating an In-polar (112¯2) InN. The valence band maximum was determined to be at (1.7 ± 0.1) eV for the (112¯2) InN sample, comparable to In-polar c-plane InN.

No abstract

Abstract. We present structure and spatially resolved composition studies by TEM (Transmission Electron Microscopy) and XANES (X-ray Absorption Near Edge Structure) of InAlN MOVPE (Metal-Organic Vapor Phase Epitaxy) epilayers containing 16-27 at% of indium. Investigations of the In L 3 edge by synchrotron radiation absorption show a significant change of the post-edge structure depending on the indium content. We attribute this to the solubility limit and phase separation in this system. Our measurements suggest that the critical composition is 18% for our growth conditions. HRTEM cross-sectional and EDX investigations confirm such phase separation as well as the changing of the structure from 2D growth to columnar like growth for the sample with the highest indium content.

Self-organized InN quantum dots were grown on GaN(0001) by metal–organic vapour phase epitaxy. Transmission electron microscopy (TEM) measurements found no wetting layer, i.e., the dots grow directly in Volmer–Weber growth mode. The dots were capped with GaN by three different procedures. Direct overgrowth at the same temperature as the dot formation produced the smoothest surfaces. Cubic and hexagonal GaN was observed in the cap layer, as well as strong indium intermixing. The dot size and volume was reduced during overgrowth. The dots were ∼90% relaxed with many dislocations at the interface from GaN to InN. The photoluminescence of the dots was very weak due to the dislocation.