有機非揮發性記憶體之量測與分析

Measurement and Analysis on Organic Oon-volatile Memory

林清偉(Ching-Wei Lin)

指導教授 ： 郭明庭 ； 李佩雯

國立中央大學/資訊電機學院/電機工程學系/碩士(2008年)

摘要

近年來由於有機複合材料具有低製造成本、高應力柔軟度和多功能用途等獨特的優勢，以及在太陽能電池、有機電晶體和發光二極體等應用上的潛力，引發廣泛的研究興趣，許多先進元件不斷被提出。在這篇論文中，我們研究一個利用有機聚合物鏈結金奈米粒子形成主動層的新穎有機非揮發性記憶體的載子傳輸機制以及記憶體本身的特性，並且提出利用橢圓儀建構出非破壞性的量測方式來精準且有效的量測有機薄膜本身的折射係數、消光係數和厚度。
　　我們可由兩層金屬中間夾著一個有機薄膜(PCm)鏈結金奈米粒子所形成主動層的記憶體元件中觀察到重覆可再現的電性雙穩態行為。從穿隧式電子顯微鏡中(TEM)，可以明顯的觀察到在有機層中的金奈米粒子分布尺寸約在3-5奈米大小，性質相當穩定。當對此元件施加一個高於臨界電壓的偏壓，元件的電流值會突然從低傳導率轉態成高傳導率，這兩個電流值的差異可達到約四個數量級。電荷在此元件中的主要電流傳導機制是Frankel-Poole穿隧，代表著載子在有機層中是藉由缺陷所形成的跳躍穿隧，而非直接穿隧。
　　對該元件進行耐久性以及資料保存能力測試，結果顯示元件在進行多次讀寫週期並不會有明顯的特性衰減，且元件對於資料的保存能力可以超過十年，這是相當良好的記憶體特性。綜合上述，如此一個新穎的有機聚合物鏈結金奈米粒子之有機非揮發性記憶體有很大的發展潛力可以應用於下一世代的發揮發性記憶體。

關鍵字

有機非揮發性記憶體

並列摘要

During the past decade, organic compounds have attracted intensively interest because of their unique advantages including low cost, high mechanical flexibility and potential applications in solar cell, organic field-effect transistors and light-emitting diodes. Many kinds of advanced memory devices were proposed. In this thesis, we investigated the carrier transport properties of a novel organic non-volatile memory device with an active layer consisting of polymer -chain-stabilized gold nanoparticles (PCm-Au NPs). A non-destructive method based on wavelength-dependent ellipsometry was proposed to characterize the PCm’s refractive index, extinction coefficient, and thickness rapidly and precisely.
We observed reproducible electrical bistability behavior in such a device consisted of a PCm-Au NPs film sandwiched between two Al electrodes. Transmission electron microscopy (TEM) observation shows that Au-NPs size is 3-5 nm and dispersed inside the organic layer. As the gate voltage exceeds the threshold voltage of 2.5V, the memory exhibited an abrupt current transition from low to high state. These two states differed in conductivity by about four orders of magnitude. The charge conduction mechanism in this system is found to be Frankel-Poole tunneling, indicating that electronic charges transport through the organic PCm layer is via trap-assisted hopping.
For practical application, the data retention and endurance properties of an Al/PCm-Au NPs/Al memory were tested under various ambient conditions. The device could be written-erased numerous times without prominent current degradation with excellent data retention ability (more than 10 years). The novel polymer stabilized Au nanoparticles bistable memory device is considered to be promising candidates for next generation nonvolatile memory applications.

並列關鍵字

organic non-volatile memory

參考文獻

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