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  • 學位論文

偏氟乙烯和三氟乙烯的共聚物在場效電晶體型記憶體元件上之應用

Application of Poly(vinylidenefluoride-co-trifluoroethylene) Copolymer on Field-Effect Transistor Type Memory Devices

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摘要


由於低溫的製程性、和軟性基材的相容性、溶液加工性、以及低成本的加工製程過程,有機(高分子)場效電晶體型記憶體元件近年來受到相當的矚目。一般而言,為了達到非揮發性記憶體元件特性,具有電荷儲存能力的介電層通常使用在記憶體元件的製程上。根據不同的操作機制,介電層的電荷儲存機制主要可細分為以下三類: (1) 電荷擷取記憶體,(2) 浮閘記憶體,以及(3) 鐵電記憶體。因此,在此碩士論文中,我們做了許多的努力在非揮發性記憶體元件的探討並著重於: (1)使用聚亞醯胺(PIs)做為高分子駐極體應於可撓性軟性基板上,和(2)單根鐵電性高分子奈米纖維應用於非揮發性電晶體型記憶體元件。 1.以聚亞醯胺駐極體為基礎之可撓性非揮發性記憶體元件於低電壓下操作(第二章): 在此章節,我們主要對以p-型 poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2) 為主動層的非揮發性記憶體元件進行探討。電荷擷取層主要是由聚醯亞胺材料(PIs)所組成,其分別是poly[2,5-bis(4-aminophenylenesulfanyl)selenophene- hexafluoro-isopropylidenediphthlimide] (PI(APSP-6FDA)) 和poly[2,5-bis(4-aminophenylenesulfanyl)thioophene-hexafluoroisopropylidenediphthalimide] (PI(APSP-6FDA))。通常,有機場效電晶體型的記憶體需要在高電壓下操作,因此為了解決這個問題,我們使用高介電常數的偏氟乙烯和三氟乙烯的共聚物 (P(VDF-TrFE))做為電荷阻漏層。在使用聚醯亞胺做為電荷擷取層後,此電晶體型的記憶體元件在低偏壓(-15V to 10 V)的範圍下,表現出良好的記憶體操作範圍(10.82 V for PI(APSP-6FDA), 和 8.63 V for PI(APST-6FDA))。除此之外,長期穩定性(~104 s),多次的切換操作性(高達100次),以及良好的可撓性(可在曲率半徑5mm下進行1000次的撓曲),展現了聚醯亞胺材料應用於非揮發性記憶體元件上的潛力。 2. 以偏氟乙烯和三氟乙烯的共聚物P(VDF-TrFE)之靜電紡絲應用於非揮發性鐵電性場效電晶體型元件(第三章): 在此章節中,我們提出了一個新穎的場效電晶體型元件。元件主要由單根的偏氟乙烯和三氟乙烯的共聚物P(VDF-TrFE)的靜電紡絲和高載子遷移速度的五環素(pentacene)所組成。在電性的表現中,此記憶體元件表現出最佳的記憶操作範圍(17.91 V)並且提升電動的遷移率至0.205 cm2V-1s-1. 除此之外,對於記憶體元件之數據儲存的能力以及操作的續航力也有仔細的討論。我們發現到使用單根P(VDF-TrFE)電紡絲做為介電層材料之非揮發性鐵電記憶體元件表現出了長時間的穩定性(~2 × 104 s)並且高導態/低導態之訊號比可維持在103,和多次的切換操作性(高達100次)。綜合以上結果,此實驗結果展現了未來利用靜電紡絲應用於記憶體元件的潛力。

並列摘要


Organic (or polymeric) field-effect transistor-type (OFET) memory devices have gained much attention over the past few years owing to their attractive features such as low processing temperature, compatible with flexible substrate, solution processibility, and low manufacturing cost. Generally, a gate dielectric layer with charge trapping/detrapping capabilities is often introduced to achieve nonvolatility of OFET devices. According to different operational mechanisms, the charge storage capability of the gate dielectric on OFET-based devices can be classified into three categories, including (1) charge-trapping memory, (2) floating gate memory, and (3) ferroelectric memory. In this thesis, a lot of efforts have been paid on the exploration of the nonvolatile OFET memory device based on (1) the incorporation of polyimide (PI) as polymer electrets on flexible substrates and (2) the utilization of single-aligned ferroelectric electrospun nanofiber as gate dielectric. 1. Low Voltage Operation of Flexible Nonvolatile Memory Devices Based on PI Electrets (Chapter 2): A p-type poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2)-based nonvolatile OFET memory device was investigated. Two polyimides (PIs), which are poly[2,5-bis(4-aminophenylenesulfanyl)selenophene- hexafluoro-isopropylidenediphthlimide] (PI(APSP-6FDA)) and poly[2,5-bis(4-aminophenylenesulfanyl)thioophene-hexafluoroisopropylidenediphthalimide] (PI(APSP-6FDA)) were used as polymer electrets, respectively. Moreover, to address the issue of a relatively high operation voltage of the OFET memory device, a high-k poly[(vinylidenefluoride-co-trifluoroethylene] P(VDF-TrFE) polymer as blocking layer was used. The OFET memory device exhibited a promising memory window of 10.82 V for PI(APSP-6FDA) and 8.63 V for PI (APST-6FDA), respectively at a sweep ranging from -15 V to 10 V. Furthermore, a long-term operational stability up to 104 s, multiple switching operation (~100 cycles), and excellent bending durability (1000 times with curvature radius at 5 mm) further made the device a promising candidate for the application of nonvolatile memory devices. 2. Nonvolatile Ferroelectric Field-Effect Transistor (FeFET) Memory Devices Based on Poly[(vinylidenefluoride-co-trifluoroethylene] P(VDF-TrFE) Electrospun Nanofibers (Chapter 3): A novel FeFET memory device consisting of aligned P(VDF-TrFE) electrospun fiber as gate dielectric and a relatively high mobility pentacene as semiconductor was explored. Maximum memory window of the device was found to be 17.91 V with enhancement in hole mobility up to 0.205 cm2V-1s-1. Moreover, the data retained capability and the operation endurance were clearly examined as well. A promising data storage capability for 2 × 104 s with the ON/OFF ratio kept at round 103 and multiple switching operation stability up to 100 cycles revealed that the device may have a potential for the application of nonvolatile memory devices.

參考文獻


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