Optical and structural characteristics of AlInN/GaN superlattices with varying AlInN fractions

Abstract

Data on the growth and characterization of AlInN/GaN superlattices (SLs) with varying AlInN fractions are presented. The SLs are grown using metal–organic chemical vapor deposition (MOCVD) and have AlInN fractions (AlInN thickness/SL period thickness) from 1 to 0.125 to explore the required GaN thickness to achieve good surface morphology. The SLs with AlInN fractions between 0.992 and 0.645 exhibited well-defined atomic steps and minimal surface defects, while lower fractions resulted in rougher surfaces. The highest AlInN fraction sample (0.992) has less than a monolayer of GaN but exhibits excellent surface morphology comparable to lower fractions. Energy-dispersive X-ray spectroscopy analysis on the highest 0.922 AlInN fraction sample revealed the expected periodic Ga incorporation but also a quaternary composition throughout with a baseline amount of Ga. Spectroscopic ellipsometry measurements demonstrated that the SLs provide refractive index tunability between GaN and AlInN. The results show that SLs maintain a smooth surface morphology across a wide range of AlInN fractions, offering excellent design flexibility for device applications.