使用矽酸鉿氧化物作為介電層形成可逆光誘導效應之非揮發性記憶元件

Abstract

此論文使用高介電常數之矽酸鉿氧化物薄膜於五苯環有機薄膜電晶體探討其記憶效應；由於矽酸鉿氧化物存在非晶矽以及晶質矽之相分離結構，適合作為電荷陷阱之材料。在電性測量上，藉由修飾層poly (a-methylstyrene)(PaMs)薄膜以旋轉塗佈方式於高介電材料上不僅能提升元件電性更增強元件記憶特性。此外，控制負閘極偏壓解釋電荷傳輸以及電荷陷阱之記憶行為；利用光激發之照光方法於正閘極偏壓施加過程中，有效地增加有機薄膜通道上的電荷載子濃度，有助於電荷傳輸並形成可逆式元件；這顯示了在非揮發記憶體元件運用上的光誘導效應對於五苯環有很大的影響。此外，更值得一提的是：單一光波長所產生的釋放電荷正比於五苯環的吸收特性；當有機薄膜對於特定波長有較強的吸收能力時，釋放電荷的速度也隨之增加，尤其是在波長為670奈米最為明顯。整體而言，以矽酸鉿氧化物介電層產生的記憶現象擁有顯著的傳導電性、高光敏性的五苯環、以及照光後所產生的鬆弛效應可作為低功率耗損、可饒式、輕薄、低操作電壓、大面積、低成本、資料儲存以及感光性的複寫記憶體元件。

This work describes the memory effect in pentacene-based organic thin-film transistors (OTFTs) with a high-dielectric gate insulator, hafnium silicate, which is a suitable material for the trapped-induced effect due to its dual-phase structure consisting of the amorphous and crystalline regions. Through the electrical measurement, enhanced field-effect as well as memory behaviors were achieved after the modification of the dielectric surface by the spin-coated poly (□-methylstyrene) (P□Ms) thin-film layer. Besides, negative gate bias was related to charge -trapping and -transfer effect that causes a shift of threshold voltage (Vth) towards negative direction. With light exposure during the process of positive gate bias, light-induced effect increased the concentration of charge carrier in the conduction channel effectively, and then led to reversible phenomena and rewrite device. There is evident that the photoinduced effect for our non-volatile memory device made a great impact on pentacene film. It is noteworthy to mention that the released charge generated by light illumination with a single wavelength was directly proportional to the absorption characteristics of pentacene. With the increase of absorption capability, the rate of released charge in pentacene layer was faster, especially at the wavelength of 670 nm. The memory phenomena on hafnium-silicate dielectric with outstanding electrical properties, a reliable high-photosensitivity of pentacene, and relaxation of the illumination effect enable to pave the way for the applications of low-consumption, flexible, lightweight, large-area, low-cost, data-storage, photo-sensitive, and rewrite device.