Transparent Floating Gate Memory Based on ZnO Thin Film Transistor With Controllable Memory Window

Abstract

The transparent floating gate memory based on zinc oxide (ZnO) thin film transistors (TFTs) was fabricated by using one-step atom layer deposition of aluminia tunneling and ZnO charge-trap layers. Free electrons trapping mechanism of this memory device is proposed after systematical investigation of gate voltage scanning and thickness of the trapping layer. Furthermore, the relationship between the geometrical size of the charge-trapping layer and the memory window is explored. The devices with different memory windows can be controlled simply by designing the area of their trapping layer without any external process, which is much beneficial to the low cost process fabrication of the memory array and driving circuits, since the memory and switch/digital transistors can be fabricated at the same time. Finally, the presented TFT memory exhibits a maximum memory window of 15 V, excellent fatigue and retention properties more than 30,000 s without any charge loss. The transparent floating gate memory with the ZnO charge-trap layer has great potential for application of 3D, transparent or multi-value memory.