Enhancing the Crystal Quality of AlN Thin Films on Patterned Sapphire Substrates Using Temperature-Modulated Growth in the PALE Technique

Abstract This study investigates the impact of temperature modulation interfaces on the quality and growth modes of aluminum nitride (AlN) thin films grown on c-plane patterned sapphire substrates using the pulsed atomic layer epitaxy technique. The thin films were grown via metal-organic vapor-phase epitaxy, where all growth parameters were kept constant except for temperature. The high temperature was maintained at 1440 °C, while the low temperature was set at 1250 °C. Three sample groups were prepared: Sample A with a high/low/high-temperature sequence, Sample B with a high/low-temperature sequence, and Sample C grown entirely at high temperature. A total of 3600 growth loops were used for each sample. Characterization by high-resolution X-ray diffraction, UV–Vis-NIR spectrophotometry, and scanning electron microscopy revealed that reducing the number of temperature modulation interfaces improves crystal quality. Sample C, grown at a constant high temperature, exhibited the best crystal quality with reduced dislocation density and smoother surface morphology. This study highlights the importance of temperature modulation in optimizing the growth and structural properties of AlN thin films for high-performance applications.