Morphology, Crystalline Quality, and Optical Properties of MOCVD-grown InN/InAlN Heterostructures

InN is a promising III-nitride material for high-speed electronics and for optoelectronic applications in the infrared. We focused on the MOCVD growth of InN films and InAlN buffer layers with InN content in the alloy x
_In
≅ 0.55 on sapphire substrate. The InN layers were about 100 nm thick and their structural, morphological, and optical properties were evaluated. Surface morphology and crystallinity of the InAlN buffer layer strongly affects the top InN film. The InAlN layer itself was markedly influenced by the preceding nitridation procedure. A decent quality of InN crystal was indicated by the PL peak at about 720 meV with a FWHM of 116 meV at room temperature. We correlated photoluminescence and XRD characteristics of the layers with their morphology. The results underline the importance of the nitridation procedure in the In(Al)N growth.