Electromechanical properties and leakage current characteristics of metal-insulator-metal diodes fabricated on polymer substrates and on glass substrates

High-performance metal-insulator-metal (MIM) devices on flexible polymer substrates without any defects (such as cracks, delamination, and blistering) and on glass substrate were successfully fabricated. This paper examines the mechanical properties of the polymer substrates and the electrical characteristics of MIM tantalum pentoxide (Ta₂O₅) films. High-quality Ta₂O₅ thin films were obtained by using an anodizing method. Also, using newly developed methods, including a stepped heating process for polymer substrates, we obtained high-performances MIM devices on polymer substrates. Here, we propose a gas barrier layer of polymer substrates in order to enhance the ductility of the Ta electrode and to prevent blistering problems. Electrical measurements were also carried out for as-deposited and thermally treated MIM devices, including Ta/Ta₂O₅/Ti structures. The MIM devices fabricated on polymer substrates and on glass substrates exhibited similar leakage current characteristics (below 10^-6 A/cm² at 1 MV/cm) and reasonable breakdown voltages (4∼7 MV/em) with a uniformity of 93 %. The current-voltage (I-V) behaviors and the conduction mechanisms of the MIM devices on both polymer and glass substrate are discussed based on the results of electrical measurements and structural investigations and on the conduction mechanism for the leakage current.