Non-volatile transistor memory fabricated using DNA and eliminating influence of mobile ions on electric properties

An organic thin-film transistor (OTFT) memory was fabricated using deoxyribonucleic acid (DNA) as a gate dielectric layer. Since natural DNA contains intrinsic ions and water molecules, the OTFT exhibited low resistivity and a low on/off ratio because of the mobile ions. In order to remove these mobile ions from DNA, it was complexed with a bulky surfactant through an electrostatic interaction. The OTFT fabricated using a DNA-surfactant complex exhibited a relatively high on/off ratio because of the decrease in the off-current. Residual ions that remained in the complex caused a decrease in the cell performance with respect to parameters such as the on/off ratio and long-term memory stability. When poly(methyl methacrylate) (PMMA) was layered on the DNA-surfactant layer, the OTFT exhibited better on-current and long-term memory stability than a typical OTFT. The pentacene layer deposited on the PMMA surface as a semiconductor had a relatively large grain size and relatively high crystallinity. This contributed to an increase in the hole mobility in the pentacene layer and the prevention of the abovementioned adverse effects of the residual ions. Consequently, the performance of the OTFT memory having the DNA complex was considerably improved.