Crystalline and optical properties of AlN films with varying thicknesses (0.4-10 µm) grown on sapphire by metalorganic chemical vapor deposition

Optical and Structural Properties of Aluminum Nitride Epi-Films at Room and High Temperature

“…Previously, different techniques, such as substrate pretreatment, interlayer insertion, annealing of nucleation layers, and strain management, have been reported to improve the quality of AlN films grown on sapphire and silicon carbide (SiC) substrates [8][9][10][11][12][13][14]. In recent years, considerable studies have been performed on AlN by our research team [15][16][17][18][19]. Research and development (R&D) on AlN is currently still at the frontier of scientific society [6,[20][21][22][23][24][25][26][27].…”

“…Extensive reports have used traditional methods such as high-resolution X-ray diffraction (HR-XRD), optical transmission (OT), and Raman spectroscopy to evaluate the structure and optical characteristics of AlN [15,18,[28][29][30]. Samiul Hasan et al [28] investigated a 4 µm thick crack-free AlN film grown on a 0.2 • offcut sapphire substrate using nitrogen as a carrier gas.…”

“…Because the bandgap energy evaluated from the analysis of reflectance spectra and photoluminescence is different, the PL measurement method can accurately measure the temperature-dependent inter-band transition energy associated with E g [30] but cannot evaluate the Urbach band tail effects below the bandgap edge. Recently, Zhe Chuan Feng et al [15] reported optical studies of AlN films with different thicknesses (0.4-10 µm) grown on sapphire using XRD, OT, SE, and Raman. However, Urbach's energy was simply studied by the spectroscopic ellipsometry (SE) method and the variation trend of the energy bandgap with temperature was not studied under hightemperature conditions.…”