For the mass production of GaN-based electronic devices, growth of AlGaN/GaN heterostructures on substrates larger than 100 mm in diameter is indispensable. In this study, we demonstrate the growth of 100-mm-diameter Al0.26Ga0.74N/GaN heterostructures on sapphire substrates by metalorganic vapor phase epitaxy (MOVPE). The obtained films have specular surfaces, good crystal quality and good uniformity of alloy composition across the entire 100-mm-diameter epitaxial wafer. The bowing value of the 100-mm-diameter epitaxial wafer on c-face sapphire substrates is about 40 µm. This bowing value seems to be preferable for electronic device fabrication processes. These epitaxial wafers show good electrical properties.

We have demonstrated AlGaN/GaN high electron mobility transistors (HEMTs) grown on epitaxial AlN/sapphire templates. The crystal qualities and fabricated device performances between AlGaN/GaN HEMTs on epitaxial AlN/sapphire templates and conventional AlGaN/GaN HEMTs on sapphire substrates with low-temperature buffer layer (LT-BLs) are compared with each other. By using epitaxial AlN/sapphire templates instead of LT-BLs, higher mobility was exhibited and superior crystal qualities were observed, as confirmed by X-ray diffraction (XRD), atomic force microscopy (AFM) images and capacitance-voltage measurements. In addition, the dc characteristics of the fabricated devices on epitaxial AlN/sapphire templates were enhanced. AlGaN/GaN HEMTs on epitaxial AlN/sapphire templates are promising candidates for practical applications of nitride-based electronic devices.