FIELD-EMISSION PROPERTIES OF GAN FILMS ON SI(111)

GaN thin films were grown by electron cyclotron resonance molecular be am epitaxy on Si(111) wafers. X-ray diffraction and transmission elect ron microscopy revealed that the thin films were single crystals with a hexagonal symmetry and a clear textured structure. The average colum n size was determined to be close to 100 nm in diameter. Despite the l arge defect density, a strong room temperature photoluminescence signa l 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 micr oscopic level with about 5 x 10(9) tips/cm(2) density. The field emiss ion characteristics of the as-grown thin films were measured, and a th reshold electric field as low as 30-40 V/mu m and an emission current density of more than 100 mA/cm(2) were obtained. (C) 1998 American Ins titute of Physics. [S0003-6951(98)01539-3].