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The nearly lattice-matched InxGa1−xN/InyAl1−yN epi-layers were grown on a GaN template by plasma-assisted molecular beam epitaxy with a metal modulation technique. The band-gap energy of InxGa1−xN QW in photoluminescence measurement was estimated to be 2.89 eV and the indium concentration (x) was 14.8%. In X-ray photoelectric spectroscopy, we obtained an indium concentration (y) in the InyAl1−yN barrier of 25.9% and the band-offset was estimated to be 4.31 eV. From the atomic layer measurements from high-resolution transmission electron microscopy, the lattice misfit between the InxGa1−xN QW and InyAl1−yN barrier was 0.71%. The lattice-matched InxGa1−xN/InyAl1−yN QWs can therefore be evaluated from the band profiles of III-nitrides for engineering of full-visible-light emitting diode in optoelectronic application. [ABSTRACT FROM AUTHOR]

We have grown a high-quality single-phase M -plane GaN on β-LiGaO2 (100) by plasma-assisted molecular beam epitaxy. The Hooke’s law for M -plane GaN was derived by a stress tenor transformation. From the analysis of M -plane GaN microstructure, the lattice strain of M -plane GaN along the [11 2 ¯ 0] and [0001] directions have been estimated. Based on the Hooke’s law, we calculated the ratio of anisotropic stress which was consistent with the ratio of thermal expansion-mismatch between GaN and LiGaO2 (100). We demonstrated that the thermal expansion mismatch was the major factor to degrade the quality of M -plane GaN on β-LiGaO2 (100). [ABSTRACT FROM AUTHOR]

• Prismatic domain cracks was found with an equivalent width (~20 nm) of In y Al 1-y N epi-layer. • The concave valley crack was showed in micro-image rather than V-shaped crack of tensile stress. • The compressive stress was the forming factor of a crack. • The crack appeared as lattice mismatch was greater than 2.4% and disappeared when the lattice mismatch was less than 1%. In y Al 1− y N epifilms with alloy compositions (y) ranging from 0.13 to 0.47 were grown on a GaN template using a low-temperature molecular-beam-epitaxy technique. Because of the larger lattice constant of high-indium-content In y Al 1− y N epifilm, the compressive stress accumulated during epitaxy. When the compressive stress exceeded the elastic limit of the In y Al 1− y N epifilms, a "concave-valley" crack with an equivalent width (~25 nm) was generated to form a prismatic domain. Our calculation and fitting results showed that no cracking occurred when the lattice mismatch was<1% because the stress was within the elastic limit. By contrast, the cracks appeared when the lattice mismatch was>2.4% because the stress exceeded the elastic limit. [ABSTRACT FROM AUTHOR]