Plasma-enhanced atomic layer deposition of crystalline GaN thin films on quartz substrates with sharp interfaces

Polycrystalline hexagonal GaN films were deposited directly on amorphous quartz (fused glass) substrates at 250 °C by plasma-enhanced atomic layer deposition. An atomically sharp GaN/quartz interface is observed from transmission electron microscopy images, which is further demonstrated by x-ray reflectivity measurements. The atomic force microscopy image reveals a smooth surface of GaN. The concentrations of oxygen and carbon impurities in GaN are 6.3 and 0.64%, respectively, according to x-ray photoelectron spectroscopy analysis. The electron mobility measured by Hall is 1.33 cm² V⁻¹ s⁻¹. The results show that high-quality GaN films are obtained on amorphous quartz substrates, and GaN/quartz can be used as a template for the fabrication of GaN-based devices.