Charge Carrier Injection Characteristics of Semiconductive and Metal Electrodes in XLPE

In this article, a method using a barrier layer to realize electrode unipolar charge carrier injection is proposed to study the injection characteristics of positive and negative charge carriers by different electrode materials. The space charge distribution in XLPE/polytetrafluoroethylene (PTFE) was measured by the pulsed electroacoustic (PEA) method, and the relationship between the accumulation rate of injected charge carriers and electric field strength at the electrode interface was further established. It was found that the aluminum (Al) electrode had a greater charge injection capability than the semiconductive layer, while both were stronger than that of the gold (Au) electrode. The combined analysis of space charge measurement results and theoretical model verified the accuracy of the relationship between the accumulation rate of injected charge carriers and electrode field to characterize charge injection behavior. Space charge measurement in single-layer XLPE samples verified its validation. This study provides techniques and theoretical guidance for the testing and development of semiconductive materials in XLPE direct-current (dc) cables.