嵌入ZnO奈米顆粒之γ-APTES薄膜多膜態電阻切換特性之研究

Investigation of Multilevel Resistive Switching in γ-APTES Film with Embedded ZnO Nanoparticles

洪友良(Yu-Liang Hung)

指導教授 ： 吳幼麟

國立暨南國際大學/科技學院/電機工程學系/碩士(2017年)

摘要

本論文主旨在於研究有機介電材料3-氨基丙基三乙氧基矽烷(3- aminopropyl- triethoxysilane, γ-APTES)與氧化鋅奈米粒(ZnO nanoparticles, ZnO NPs)依不同比例混合後應用於電阻切換記憶體元件之研究。在本論文中，我們比較摻入固定比例ZnO奈米粒之不同濃度及不同旋塗次數(介電層厚度)的γ-APTES薄膜對元件電阻切換特性之影響。
我們先調配好不同濃度之γ-APTES旋塗溶液，並額外調配一組相同濃度的γ-APTES/ZnO NPs(0.1%)混合液做為對照組；接著，對氟化氧化錫導電玻璃(FTO)基板進行RCA clean，然後利用旋塗機將先前配置好的兩組旋塗溶液分別旋塗在兩片不同的基板上，旋塗完畢後進行退火，退火溫度因多次嘗試後選擇攝氏120度5分鐘為本實驗的退火溫度，最後用蒸鍍機(Evaporater)透過金屬遮罩(metal mask)蒸鍍鋁(Al)做為頂電極，如此一來即可得到Al/γ-APTES/FTO、Al/γ-APTES+ZnO NPs/FTO兩組樣品。
完成製程步驟後接著進行量測步驟，我們使用半導體參數分析儀Agilent 4156B以掃描(SWEEP)模式對元件進行I-V特性量測，由量得的I-V特性決定元件的電阻切換特性。另外，同樣以Agilent 4156B選擇(SAMPLING)模式量測元件的retention特性；量測方式我們將頂電極鋁(Al)訂為正極，底電極FTO導電玻璃訂為底電極，進行量測；結果顯示，當介電層厚度相同時，1%的γ-APTES旋塗溶液比0.1%的γ-APTES旋塗溶液有較好的多模態表現，猜測可能是因為較高濃度的旋塗溶液有較多的γ-APTES粒子；而在相同的濃度下，旋塗一次(厚度:0.019um )跟旋塗三次(厚度:0.045um ) 比起來，不管是阻態切換或是多模態的表現都有較顯著的特性，推測可能是在相同電壓下，介電層中的電場較低使得電子較不易在氧空缺形成的倒電路徑中傳導之故；最後，在相同濃度的γ-APTES溶液中加入ZnO NPs與本來沒加ZnO NPs的溶液相比較，可以發現加入ZnO NPs後會減少阻態切換次數，進而影響多模態特性，至於retention特性量測部分，相同濃度下有加入ZnO NPs與沒加入ZnO NPs的高阻態(Resistance of High Resistance State, HRS)與低阻態(Resistance of Low Resistance State, LRS)的電流穩定度是差不多的，值得一提的是，加入ZnO NPs後元件所量測到的電流不管是RHRS或是RLRS都較沒加入ZnO NPs的高；由於ZnO NPs是導電性的奈米粒子，加上先前數據所證實若在γ-APTES溶液中加入ZnO NPs的確會降低元件的電阻值。

關鍵字

有機電阻式記憶體 ； 氧化鋅奈米顆粒 ； 3-氨基丙基三乙氧基矽烷

並列摘要

The main theme of this thesis is to study the resistive switching characteristics of organic insulator material 3-aminopropyltriethoxysilane (γ-APTES) embedded without or with zinc oxide nanoparticles (ZnO NPs). With fixed mixed ratio of ZnO nanoparticles, we also investigated the effect of various concentrations as well as different thicknesses (by different numbers of spin coating) of -APTES on the resistive switching properties of the memory devices.

In this work, we prepared solutions with different -APTES concentrations for spin coating. For comparison, we also prepared a solution with a fixed -APTES/ZnO NPs ratio (= 0.1%). After RCA cleaning process, the solutions prepared were then spin-coated onto fluorinated tin oxide (FTO) substrates, followed by a 120℃, 5 min baking on hotplate. Finally, an Al top electrode was evaporated on the sample via metal mask. The completed devices have structures of Al/-APTES/FTO and Al/-APTES+ZnO NPs/FTO, respectively.

For devices characterization, semiconductor parameter analyzer Agilent 4156B was used to measure the I-V characteristics under SWEEP mode and retention property under SAMPLING mode. From the I-V characteristics, we can determine the resistive switching of the devices. For each measurement, the top Al electrode was biased positively and bottom FTO electrode negatively. Our experimental results show that, for the same -APTES thickness, better multi-level resistive switching characteristics were found in device with 1% -APTES than the one with 0.1%. It is believed that more conducting paths would be formed in the layer with higher -APTES concentration for more oxygen vacancies existed. It is also noticed that, for fixed -APTES concentration, the device prepared by one-time spin coating can have the better resistive switching characteristics than the one prepared by three-time spin coating. We infer that lower electric field induced in thicker -APTES film defers the electron conduction in conducting paths formed by oxygen vacancies.

Finally, we compared the resistive switching characteristics of devices prepared with fixed -APTES concentration but mixed with and without ZnO NPs. it is found that the number of multi-level switching reduces after the device is being added with ZnO NPs. As for retention property, it is found that the devices with fixed -APTES concentration mixed either with or without ZnO NPs has similar current stability under high-resistance and low-resistance states. It is worthy of mention that adding ZnO NPs increases the current level for both high-resistance state and low-resistance state of the devices, indicating that the resistance of the insulator layer is reduced.

並列關鍵字

Organic RRAM ； zinc oxide nanoparticles ； (3-aminopropyl) triethoxysilane

參考文獻

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