Field emission properties of GaN films on Si(111)

GaN thin films were grown by electron cyclotron resonance molecular beam epitaxy on Si(111) wafers. X-ray diffraction and transmission electron microscopy revealed that the thin films were single crystals with a hexagonal symmetry and a clear textured structure. The average column size was determined to be close to 100 nm in diameter. Despite the large defect density, a strong room temperature photoluminescence signal with a full width at half maximum of 138 meV was observed from these samples. The surface exhibited random array of sharp tips at the microscopic level with about 5×109 tips/cm2 density. The field emission characteristics of the as-grown thin films were measured, and a threshold electric field as low as 30–40 V/μm and an emission current density of more than 100 mA/cm2 were obtained.