Two In Al 1− N layers were grown simultaneously on different substrates (sapphire (0001) and Ga-polar GaN template) but under the same reactor conditions were employed to investigate the mechanism of strain-driven compositional evolution. The resulting layers on different substrates exhibit different polarities and layer grown on sapphire is N-polar. Moreover, for the two substrates, the difference in degree of relaxation of the grown layers was almost 100%, leading to a large In-molar fraction difference of 0.32. Incorporation of In in In Al 1− N layers was found to be significantly influenced by strain imposed by the under-layers. The evolutionary process of In-incorporation during subsequent layer growth along [0001], the direction of growth was investigated in detail by Auger electron spectroscopy. It is discovered that In 0.60 Al 0.40 N layer grown directly on sapphire consist of two different regions with different molar fractions: transition and uniform region. According to the detailed cross-sectional transmission electron 2 microscopy, the transition region is formed near the hetero-interface due to the partial strain release caused by the generation of misfit-dislocations. The magnitude of residual strain in uniform region decides the In-molar fraction. In Al 1− N layers were analyzed by structural and optical characterization techniques. Our present work also shows that multi-characterization approach to study In Al 1− N is prerequisite for their applications as a buffer layer.

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The study focused on object formation in (100) InP by etching in 3HCl:1H3PO4 through convex and concave square mask patterns of varied orientation and size. Their upper right-hand-side corners were aligned to , and to 15°, 30° and 45° off to . Some -oriented convex squares had - and -oriented corners compensated with rectangular extensions. The concave patterns led to objects with ordinary slow-etching or etch-stop facets along sides in line within and with ordinary and re-entrant facets along sides in line within . The convex patterns (, 15° and 30°) led to objects initially confined by fast-etching facets at corners and slow-etching or etch-stop facets at sides (ordinary between and , and re-entrant between and ). The side facets were eliminated by the progress of the corner ones. They (-oriented patterns) proceeded at rates almost independent of size before the eradication of the side facets, after which they proceeded faster. The -oriented convex patterns led to objects confined only by fast-etching facets. The objects developed at rates that considerably depended on pattern size and etching time. Objects under small patterns developed faster compared to those under large ones. The -oriented corner-compensated patterns led to pyramidal objects confined by facets related to (110), , (101) and .

InAlN as a functional inorganic material is a promising alternative to the commonly used InGaN in tunnel diodes and optoelectronic devices, due to its tunable wider range of energy bandgap (0.65-6.2 eV), thus empowering utilization of the whole solar spectrum. Moreover, high electron drift velocity and carrier concentration are considered as the most desirable prerequisite of indium-rich InAlN. N-polar indium-rich InAlN could be more beneficial due to the reverse direction of the polarization compared to Ga-polar. However, unanswered questions persist concerning growth evolution of N-polar indium-rich InAlN grown by organometallic chemical vapor deposition (OMCVD). In this study, energy dispersive X-ray spectroscopy (EDX) and high-angle annular dark-field (HAADF) imaging are used to characterize N-polar layer at nanometer scale in order to determine the evolution of the layer on (0001) sapphire substrate. Long nitridation of sapphire substrate leading to the formation of~2 nm AlON ultrathin interlayer, which relaxes strain at the InAlN/sapphire interface with assistance of a low-temperature AlN interlayer is observed. EDX analysis confirms that after strain relaxation of InAlN layer, the indium-incorporation has only a weak dependence on the polarity of the layer. The incorporation of indium at preferential sites is also discussed at length.