INTERNAL PHOTOEMISSION IN EVAPORATED AL-AL2O3-AL THIN FILM DEVICES.
AIR FORCE AVIONICS LAB WRIGHT-PATTERSON AFB OHIO
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The results of a study of internal photoemission in evaporated Al-Al2O3-Al thin-film sandwiches will be presented. The dielectric films for these samples were prepared by electron-beam evaporation from a sapphire rod. This material has a dielectric constant of about 7.5. Film thicknesses were measured capacitively, interferrometrically, and with a quartz-crystal-oscillator microbalance, all of which gave internally consistent results. The photoresponse was measured at room temperature as a function of wavelength at different bias voltages for dielectric films ranging in thickness from about 100 A to less than 40 A. The results, interpreted in terms of metal-insulator barrier height, indicate that the barrier shape is trapezoidal but that the asymmetry decreases abruptly for dielectric thicknesses below about 60 A. The zero-bias barrier height was found to be 1.8 eV for the 42-A films, and it increased rapidly with dielectric thickness. These results will be discussed in terms of the current theories of metal-insulator-metal thin-film devices. Author
- Electrical and Electronic Equipment
- Electricity and Magnetism
- Solid State Physics