Saturation Current Produced by Exponential Decrease in Local Mobility in Low-density Polyethylene with Charge Packet

抄録

This paper presents an experimental study on saturation current for a low-density polyethylene (LDPE) with a semiconduction- anode and aluminum-cathode system under various temperatures. The current density at 30°C saturates and then finally decreases though the applied field E increases step by step from 0.1 to 1.5 MV/cm. The space charge distributions at 30°C are quite different from the theoretical distributions based on the space-charge-limited current model with a constant mobility. A large number of positive charges are injected from the anode and then they form a large packet in the LDPE bulk near the cathode, so that the field distribution is strongly distorted. The saturation current with the charge packet implies that local mobility at the positively charged region is much smaller than that at the other regions. The local mobility calculated with an assumption that only the positive charges are injected into the LDPE bulk exponentially decreases with increasing E at 30°C.