Development of a space charge measurement method without a semiconducting electrode

To develop an electrode configuration without a semiconducting electrode for space charge measurements, a hemispherical steel electrode with a rough surface was used as the upper electrode in the pulsed electroacoustic (PEA) method to obtain acoustic matching with the sample. The space charge distributions of a polymer film were measured using various electrode configurations. As a semiconducting electrode was inserted between the ethylene vinyl acetate copolymer (EVA) and the hemispherical steel electrode, the polarity of the space charge accumulated in the bulk agreed with that of the semiconducting electrode and the hemispherical steel electrode. Although some carriers related to impurities in the semiconducting electrode might affect space charge formation in the film, the polarity of the accumulated space change remained the same regardless if the semiconducting electrode was inserted between EVA and the hemispherical steel electrode. Hence, this new electrode configuration without a semiconducting electrode is beneficial because the space charge property in the film on the evaporated electrode system is clear.