Low-temperature epitaxial growth and photoluminescence characterization of GaN

Epitaxial layers of GaN on sapphire substrates have been grown by metalorganic chemical-vapor deposition at a deposition temperature as low as 400°C, which is the lowest temperature for successful epitaxial growth of GaN by any technique. This is achieved by controlling the low flow rate of the source gases and by first depositing an AlN buffer layer at 400°C. Low-temperature photoluminescence measurements have been employed to study the optical properties of the films deposited at different temperatures.