RESEARCH ON DIELECTRICS FOR MICROWAVE ELECTRON DEVICES.

摘要

The purpose of this research was to study the properties of dielectrics used in microwave devices with special emphasis on materials used for microwave windows. This report reviews the results of a study of the transport and breakdown properties of aluminum oxide and of methods of growth of this dielectric from the vapor phase in an evacuated system. Growth of aluminum oxide films ranging in thickness from 1000to 5000angstroms by five different methods was achieved. Alpha aluminum oxide films were grown by thermal evaporation in the ultrahigh vacuum system. Data from experiments on transport in single crystal sapphire indicate that electron or hole conduction is primarily due to the effect of impurities or defects and,therefore,indicates either an impurity band or hopping process or a polaron conduction mechanism. The data from electron bombardment and breakdown studies indicate that particle bombardment,in addition to creating defects if particle energy is sufficiently high,can also lead to formation of separated charge regions in the material. These regions can act as sources of internal fields within the dielectric. (Author)