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 degrees 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.