A method for depositing a Group III nitride semiconductor film on a substrate is provided that comprises: providing a sapphire substrate; placing the substrate in a vacuum chamber; conditioning a surface of the substrate by etching and providing a conditioned surface; holding the substrate away from a substrate facing surface of a heater by a predetermined distance; heating the substrate to a temperature by using the heater whilst the substrate is held away from the substrate facing surface of the heater, and depositing a Group III nitride semiconductor film onto the conditioned surface of the substrate by a physical vapour deposition method whilst the substrate is held away from the substrate facing surface of the heater and forming an epitaxial Group III nitride semiconductor film with N-face polarity on the conditioned surface of the substrate.