A planar metal-insulator-semiconductor (MIS)-type field emitter using epitaxial gamma-Al2O3 (111)/Si(111) structure was successively fabricated and field-emission phenomena were observed. Planar MIS-type field emitters using epitaxially grown Al2O3 were fabricated by molecular beam epitaxy (MBE) method and characteristics of these emitters were evaluated. It was confirmed that the Al2O3 possessed good crystalline quality and surface morphology. The breakdown field of the epitaxial Al2O3 layer was able to increase in situ annealing at the substrate temperature of 750 degreesC. From experimental measurements of diode current, conduction band offset (DeltaEc) value between the epitaxial gamma-Al2O3 and Si (111) substrate was calculated to be 2.5 eV. Fowler-Nordheim (F-N) tunneling was observed from the 8-nm-thick epitaxial Al2O3 film. Emission characteristics were obtained from the 10-nm-thick epitaxial Al2O3 insulator with a 20-nm-thick At gate electrode. The maximum transfer ratio of emission current was confirmed to be 1%. 0 2004 American Vacuum Society.