AlN Thin Films Grown on Different Substrates by Metal Nitride Vapor Phase Epitaxy

In this paper, AlN thin films are fabricated by green and efficient metal nitride vapor phase epitaxy (MNVPE). First, AlN films are grown on c-plane sapphire substrates at different molar flow ratios (V/III ratios) of the source material, and the effects of V/III on the crystal quality and surface morphology of the films are investigated. The growth conditions are kept constant (growth temperature of 1550 degrees C, growth pressure of 10 kPa, V/III ratio of 4420), and the AlN thin films are prepared by heterogeneous epitaxial growth on c-plane sapphire, silicon (111), and GaN substrates. The crystal quality, residual stress, and luminescence properties of epitaxial AlN thin films on the three substrates are investigated using X-ray diffraction, scanning electron microscopy, Raman spectroscopy, photoluminescence, and UV spectrophotometer. Among them, the FWHM value of the sample AlN/GaN (002) plane can reach 338 arcsec. The residual stress in samples AlN/Sapphire, AlN/GaN and AlN/Si are 1027, -81, and -541 MPa, respectively, and the sample AlN/GaN has fewer point defects. At the same time, a 50-nanometer-thick void layer appears in the AlN thin film samples prepared on GaN substrates, which provides a new technical idea for realizing large-scale and high-quality self-supporting AlN thin films.