A DC plasma oxidation system with a hollow cathode which consists of a pair of parallel Si plates was developed. Using this system, thin Si oxide films of less than 40 nm thickness were grown on n-type Si(100) substrates, for the application to the tunnel devices. The film quality and the oxide stoichiometry were estimated by XPS measurements. On the oxide films, the MIS (Metal-Insulator-Semiconductor) diode type tunnel emitters were fabricated. The electrical properties of the diodes, such as I-V characteristics and electron emission into the vacuum were measured. For a typical sample, an electron emission current density of 800 pA/mm(2) into the vacuum was obtained.