Improved surface morphology and reduced V-pits density of lattice-matched AlInN films grown by atmospheric pressure metalorganic chemical vapor deposition

AlInN has emerged as a promising material for advanced optoelectronic and electronic devices due to its unique properties. However, achieving AlInN layers with excellent surface morphology remains challenging. Here, Al0.83In0.17N layers lattice-matched to GaN/sapphire were grown by atmospheric-pressure metalorganic chemical vapor deposition at 875 degrees C. The lowest surface roughness measured by atomic force microscopy was 0.37 nm after optimizing the growth temperature and flux of precursors. The roughness value was constant in the range of 15-72 nm film thickness. Introducing a TMI pre-flow period before AlInN growth, further reduced roughness to 0.28 nm, although a graded inclusion of Ga into the AlInN near the GaN/AlInN interface was observed. This improved surface morphology was interpreted by the In-surfactant effect enriched by the pre-flow in the early stage of AlInN. Additionally, the V-pits density was as low as 2x10(5) cm(-2), primarily due to high growth pressure and also influenced by relatively high growth temperature. Analysis of Al incorporation using second-order reaction model suggests that the severe parasitic reactions between TMA and NH3 at atmospheric pressure can be effectively eliminated by a high total gas flow rate of 72 slm, ensuring in-plane uniformity in surface morphology and relatively good crystalline quality.