Growth and properties of Al-rich InxAl1−xN ternary alloy grown on GaN template by metalorganic chemical vapour deposition

An Al-rich InxAl1−xN ternary alloy was grown on a GaN template by metal–organic chemical vapour deposition (MOCVD). The GaN template was fabricated on a c-plane sapphire with a low temperature GaN nucleation layer. The growth of the 300 nm thick InxAl1−xN layer was carried out under various growth temperatures and pressures. The surface morphology and the InN molar fraction of the InxAl1−xN layer were assessed by using atomic force microscopy (AFM) and high resolution x-ray diffraction, respectively. The AFM surface images of the InxAl1−xN ternary alloy exhibited quantum dot-like grains caused by the 3D island growth mode. The grains, however, disappeared rapidly by increasing diffusion length and mobility of the Al adatoms with increasing growth temperature and the full width at half maximum value of ternary peaks in HR-XRD decreased with decreasing growth pressure. The MOCVD growth condition with the increased growth temperature and decreased growth pressure would be effective to grow the InxAl1−xN ternary alloy with a smooth surface and improved quality. The optical band edge of InxAl1−xN ternary alloys was estimated by optical absorbance and, based on the results of HR-XRD and optical absorbance measurements, we obtained the bowing parameter of the InxAl1−xN ternary alloy at b = 5.3 eV, which was slightly larger than that of previous reports.

Source:IOPscience

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