Characterization on the operation stability of mechanically flexible memory thin-film transistors using engineered ZnO charge-trap layers

Abstract

The charge-trap memory thin-film transistors (CTM-TFTs) using ZnO charge-trap layer (CTL) were fabricated and characterized, in which ZnO CTL was deposited by atomic layer deposition (ALD) and the deposition temperatures were controlled to be 75, 100, and 125 °C to improve both specifications of device characteristics and stability for the flexible memory devices. The CTM-TFT using ZnO CTL deposited at 100 °C obtained a wide memory window (MW) of 14.7 V, large memory margin between ON- and OFF-states (ION/IOFF, 7.3 × 106) at 1 µs voltage pulses. The ION/IOFF larger than 107 was also obtained with a progress of retention time. It was noteworthy that the deposition temperature for the ZnO CTL was worked as one of the most important control parameters affecting the memory device characteristics of the fabricated flexible CTM-TFTs. Alternatively, the fast program operation and long retention time were suggested to result from a suitable number of trap sites and their appropriate positions within the ZnO CTL prepared at 100 °C. The improved device stabilities were guaranteed even under bending condition at a radius of curvature of 10 mm after the delamination process of PI film substrate from carrier glass.