Thermally stimulated exoelectron emission caused by micro defects in insulator coatings

The thermally stimulated exoelectron emission (TSEE) is considered to be effective for detection of the micro defects of the insulator thin layer coated on a certain substrate. Such micro defects are, for example, induced in the alumina coating by forcing the substrate of stainless steel (SUS-304) to bend repeatedly with a certain stress. It has been confirmed that there exists approximately a linear relation between the yield of TSEE and the number of repeated cycles, which means that the metal fatigue of the substrate could be found out in the early stage by observing the TSEE. It is also clarified that the exoelectrons are only emitted from the crystal of alpha-alumina, which could be formed either by the plasma CVD (Chemical Vapor Deposition) method with a substrate temperature of 900 degrees C or by the IVD (Ion Beam and Vapor Deposition) method without healing of the substrate.