Bistable electrical switching and performance of a pentacene-based write once/read many memory device

In recent years, organic memory devices with an active layer sandwiched between two electrodes have attracted much attention as future information storage devices [1–5]. The demand on organic non-volatile memory devices increases rapidly due to their simplicity in device structure, good scalability, low cost potential, low power operation and large capacity for data storage. Electrical bistable switching phenomena have been observed and reported for a variety of organic materials and device structures [1–10]. Several conductance mechanisms are also reported to explain this switching phenomenon. Different types of organic memory devices are: random access memory, re-writable memory and write once/read many memory (WORM). WORM memory is a type of non volatile memory that is capable of storing data permanently and being read from repeatedly. Thus it is potentially applicable for permanent data storage, such as wireless identification tags, smart cards, etc. Lidan Wang et al. [11] demonstrated a non volatile organic WORM memory device based on CuPc/F16CuPc p–n junction. Shengwei Shi et. al. [12] fabricated an organic electrical memory device with a simple structure based on a single layer pentacene film embedded between Al and ITO electrodes. Bin Li et. al. [13] reported the impact of electrode metals on a pentacene based WORM device. They found that devices with Fe electrodes have lower threshold voltages. However, in terms of application, organic memory devices are often characterized by their performance and materials with good reliability need to be developed. In this work, we fabricated a write once/read many memory device with vacuum evaporated pentacene on ITO coated glass substrate with aluminium as the top electrode and the performance of the fabricated device was studied and compared with a device with an additional layer of C60.