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Abstract: We report on the growth of semipolar AlN by metal-organic vapor phase epitaxy on sapphire. High temperature nitridation and nucleation at a V/III ratio of 1050 provide single phase AlN with mirror like crack free surfaces, even for layer thicknesses larger than . Increasing reactor pressure results in lower growth rates because of gas phase particle formation. The in-plane relationship is and and therewith similar to MBE grown AlN and MOVPE and HVPE grown GaN on m-plane sapphire. The AlN reflex is anisotropically broadened in XRD. The surface shows an undulation along as typical for oriented nitride epilayers. Transmission spectroscopy measurements exhibit a sharp absorption edge at 5.95eV, which is 130meV shifted towards lower energies compared to c-plane AlN. [Copyright &y& Elsevier]

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

Abstract: We report on the growth of semipolar AlGaN in the entire composition range on sapphire by metal–organic vapor phase epitaxy. Growth rates increase linearly with the metal–organic supply and have been realized up to . The Al content determined by photoluminescence and transmission measurements depends linearly on the Al/Al+Ga ratio in the gas phase. The growth rate and the Al incorporation are higher for AlGaN than for (0001) AlGaN. This is attributed to different adatom mobility and desorption. The in-plane relationship of AlGaN is and [0001], as typical for semipolar nitrides on m-plane sapphire. For Al contents up to 60% triangle-like structures dominate the surface. For Al contents above 70% it transforms into an undulation along and additional dot-like structures. The smoothest surface morphologies with a rms roughnesses of 2nm were achieved for Al mole fractions of . [Copyright &y& Elsevier]

Abstract: Our study reports on the microstructure of AlN layers grown on m-plane sapphire by metal organic vapor phase epitaxy. We have found that AlN can nucleate with three different orientations on the m-plane sapphire surface: semipolar (112̄2) and (11̄03) as well as m-plane (11̄00). Depending on the growth conditions, i.e. V/III ratio, the differently oriented crystallites exhibit different lateral and vertical growth rates. At a low V/III ratio of 626 the vertical growth rate of semipolar (112̄2) AlN regions is much lower than that of the (11̄03) and (11̄00) oriented grains, which results in an almost complete lateral overgrowth of the (112̄2) AlN oriented regions. In contrast, a high V/III ratio of 1043 leads to the formation of uniform semipolar (112̄2) AlN layers. Nevertheless, the formation of differently oriented AlN crystallites could not be suppressed completely. These randomly appearing crystallites still show a high vertical growth rate and lead to a deterioration of the surface morphology. [Copyright &y& Elsevier]