本文選題：氧化石墨烯 + 阻變存儲器��； 參考：《山東大學》2012年碩士論文

【摘要】：隨著信息技術(shù)的發(fā)展,高速度和高密度非易失性存儲器(non-volatile random access memory, NVRAM)的發(fā)展成為一種必然趨勢。傳統(tǒng)的硅基存儲器已接近其物理和工藝極限,因此,近年來各種新型的NVRAM便得到了迅速發(fā)展。其中,ReRAM具有存儲密度高、功耗低、讀寫速度快、反復操作耐受力強、數(shù)據(jù)保持時間長、與CMOS工藝兼容、更重要的是可縮小性好(非電荷存儲機制)等優(yōu)點,并因此成為這些新型存儲器中最有應用前景的候選者之— ReRAM單元有著簡單的“三明治”(metal-insulater-metal, MIM)結(jié)構(gòu),中間絕緣阻變層的選擇對器件性能起著至關(guān)重要的作用�；贕O阻變層的材料既具有有機材料成膜簡單、膜層薄、成本低、可大面積溶液處理等優(yōu)點,又具有無機材料器件性能好、穩(wěn)定性好、壽命長等優(yōu)勢。因此,本文著力于研究氧化石墨烯及其阻變存儲器的制備和性能研究。 本論文中,首先對采用Modified Hummers'法制備的GO進行表征；其次采用旋涂工藝制備GO膜,成功制備了Al/GO/ITO ReRAM器件,并對其進行電學測試及機理分析；最后對不同退火處理下的器件進行了GO膜的表征及器件的I-V測試。本論文的研究工作及結(jié)果如下： (1)GO的制備及表征 Modified Hummers'法制備的GO在水中良好的分散性證實了GO上豐富的氧官能團。AFM數(shù)據(jù)則顯示了GO的1.1nm左右的厚度及數(shù)百納米至數(shù)微米的橫向尺寸,表明了GO的完全剝離；隨后的Raman光譜數(shù)據(jù)顯示GO相比石墨而言有著更強的D峰和更弱的G峰,即更大的ID/IG和更小的I2D/IG,這表明了石墨烯平面上sp3平均尺寸的增加；XRD的數(shù)據(jù)顯示GO有著0.93nm的層間距,證明了GO的成功插層以及石墨烯平面上sp3平均尺寸的增加；XPS分析則表明GO中含有豐富的羥基、羧基和羰基,且羥基占有很高的比重；此外,TGA測試數(shù)據(jù)顯示了GO的質(zhì)量隨溫度變化而減少的特性,進一步證實了GO中含有豐富的氧官能團。 (2) Al/GO/ITO ReRAM器件的阻變特性及機理分析 (a)阻變特性分析 Al/GO/ITO ReRAM器件在150℃退火后展現(xiàn)了極好的阻變特性,有著1.3V的置位電壓,-2V的復位電壓,約103的開關(guān)比。 耐久性測試表明器件的開關(guān)比在100次循環(huán)后仍保持不變。器件的記憶時間測試則表明其有著長達104s以上的數(shù)據(jù)保存能力。此外,限制電流關(guān)系測試結(jié)果顯示器件的復位電流密度和復位電壓隨著限制電流的增加而增加,器件的低阻態(tài)電阻隨著限制電流的增加而減少。 (b)阻變機理分析 電形成循環(huán)方向的機理分析表明：正向電形成循環(huán)后,器件有著穩(wěn)定的低阻態(tài)和高阻態(tài),這種結(jié)果是由于GO在電偏壓下的sp3雜化和sp2雜化間的轉(zhuǎn)化或表面層處的氧遷移。隨后的負向電形成循環(huán)展現(xiàn)出了WORM的特性,我們分析這種非對稱的電形成循環(huán)特性來源于器件的非對稱性。 J-V特性的機理分析表明器件的J-V特性符合SCLC關(guān)系,與阻變來自于氧空位的遷移有著良好的符合度。 電極單元尺寸依賴的機理分析表明：無論是高阻態(tài)還是低阻態(tài),器件單元的電流與電極尺寸均存在著線性關(guān)系,表明器件的阻變發(fā)生在整個接觸面,因此器件的機理并非sp3態(tài)與sp2態(tài)間轉(zhuǎn)變的細絲機理,而是電偏壓下氧官能團的遷移所引起的表面勢壘的變化。 (3) GO ReRAM與退火溫度的關(guān)系 (a)GO阻變層與退火溫度的關(guān)系 AFM膜厚分析表明GO膜的膜厚隨著退火溫度的升高而減��；粗糙度分析則表明不同退火溫度下的GO膜均有著良好的均勻性。Raman光譜分析表明隨著退火溫度的增加,GO中sp2區(qū)域平均大小逐漸增加。XRD數(shù)據(jù)表明了退火后GO中石墨結(jié)晶程度的增加,即石墨化程度的提高。XPS分析則表明C=C隨著退火溫度的升高而逐漸增加,對應著GO中sp2區(qū)域的增加,氧官能團的減少。 (b) GO ReRAM的性能與退火溫度的關(guān)系 通過對不同退火溫度下器件的測試,我們發(fā)現(xiàn)Original Sample和Annealing150℃樣品有著相同量級的開關(guān)比,而Annealing200℃和Annealing250℃樣品的開關(guān)比則逐漸減少,達到10的數(shù)量級。這種開關(guān)比的變化可能來自于氧官能團的減少。
[Abstract]:With the development of information technology, the development of high speed and high-density non-volatile memory (non-volatile random access memory, NVRAM) has become an inevitable trend. The traditional silicon based memory is close to its physical and technological limits. Therefore, in recent years, various new types of NVRAM have been developed rapidly. Among them, ReRAM has a high density of storage, Low power consumption, fast reading and writing speed, strong repeated operation tolerance, long data retention time, compatible with the CMOS process, and more important is the advantages of good scalability (non charge storage mechanism) and so on, and thus become the most promising candidates in these new types of memory.
The ReRAM unit has a simple "sandwich" (metal-insulater-metal, MIM) structure. The selection of the intermediate insulation resistance layer plays a vital role in the performance of the device. The material based on the GO impedance layer has the advantages of simple film formation, thin film, low cost, large area solution treatment and so on. It also has good performance in inorganic materials. It has good stability and long life. Therefore, this paper focuses on the preparation and properties of graphene oxide and its resistive memory.
In this paper, the GO which was prepared by the Modified Hummers'method was first characterized. Secondly, the GO film was prepared by the spin coating process, and the Al/GO/ITO ReRAM device was successfully prepared. The electrical test and mechanism analysis were carried out. Finally, the characterization of the GO film and the I-V test of the devices under different annealing treatments were carried out. The results are as follows:
(1) preparation and characterization of GO
The good dispersibility of GO in water prepared by the Modified Hummers'method shows that the abundant.AFM data on GO show the thickness of 1.1nm in the GO and the transverse dimensions of several hundred nanometers to several microns, indicating the complete stripping of GO, and the subsequent Raman spectral data shows that GO has a stronger D peak and a weaker G peak than the graphite. The larger ID/IG and smaller I2D/IG show an increase in the average size of SP3 on the graphene plane, and the data of XRD show that GO has a 0.93nm interlayer space, which proves the increase of the successful intercalation of GO and the increase of the SP3 average size on the graphene plane, and XPS analysis shows that the GO contains rich hydroxyl, carboxyl and carbonyl groups, and the hydroxyl group is very high. In addition, the TGA test data show that the quality of GO decreases with temperature, which further confirms that GO is rich in oxygen functional groups.
(2) resistance variation characteristics and mechanism analysis of Al/GO/ITO ReRAM devices
Analysis of (a) resistance change characteristics
The Al/GO/ITO ReRAM device exhibits excellent resistance characteristics after annealing at 150 C, with a 1.3V setting voltage, a reset voltage of -2V, and a switching ratio of about 103.
The durability test shows that the switch ratio of the device remains unchanged after the 100 cycle. The memory time test of the device shows that the device has the data preservation capacity of more than 104s. In addition, the limiting current relation test results show that the reset current density and reset voltage increase with the increase of the Limited current, and the device has low resistivity. The resistance decreases with the increase of the limiting current.
Analysis of (b) mechanism of resistance change
The mechanism analysis of the cycle direction of electric formation shows that the device has a stable low resistance state and a high resistance state after the forward formation cycle. This result is due to the transformation of the SP3 hybrid between the GO and the SP2 hybrids under the electric bias or the oxygen migration at the surface layer. The subsequent negative electric formation cycle shows the characteristics of the WORM, and we analyze this asymmetry. The electrical forming cycle characteristics originate from the asymmetry of the device.
The mechanism analysis of J-V characteristics shows that the J-V characteristic of the device is in line with the SCLC relationship, which is in good agreement with the migration of oxygen barrier.
The mechanism analysis of the size dependence of the electrode element shows that there is a linear relationship between the current of the device unit and the size of the electrode, indicating that the device's resistance occurs at the entire contact surface, so the mechanism of the device is not the filament mechanism of the transition between the SP3 state and the SP2 state, but the migration of the oxygen functional group under the electric bias. The change of the surface barrier caused.
(3) the relationship between GO ReRAM and annealing temperature
The relationship between the (a) GO resistance layer and the annealing temperature
The AFM film thickness analysis shows that the film thickness of the GO film decreases with the increase of annealing temperature, and the roughness analysis shows that the GO films at different annealing temperatures have a good uniformity.Raman spectrum analysis. The average size of SP2 region in GO increases gradually with the increase of the annealing temperature, which indicates the degree of the graphite crystallinity in the annealed GO. The increase of the degree of graphitization by.XPS analysis shows that C=C increases with the increase of annealing temperature, which corresponds to the increase of the SP2 region in GO and the decrease of oxygen functional groups.
The relationship between the performance of (b) GO ReRAM and the annealing temperature
By testing the devices at different annealing temperatures, we found that the Original Sample and Annealing150 centigrade samples have the same magnitude of switching ratio, while the switching ratio at Annealing200 and Annealing250 degrees decreases gradually, reaching a magnitude of 10. The change of this switching ratio may come from the reduction of oxygen functional groups.

【學位授予單位】：山東大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TP333

【參考文獻】

相關(guān)期刊論文 前2條

1 程開富,劉心蓮;電子束蒸發(fā)技術(shù)[J];電子工業(yè)專用設(shè)備;1991年01期

2 左青云;劉明;龍世兵;王琴;胡媛;劉琦;張森;王艷;李穎_";;阻變存儲器及其集成技術(shù)研究進展[J];微電子學;2009年04期

相關(guān)碩士學位論文 前4條

1 王磊;利用超臨界二氧化碳系統(tǒng)刻蝕SiO_2的研究[D];山東大學;2011年

2 李哲鋒;PEDOT：PSS基有機自旋電子材料與器件制備及結(jié)構(gòu)性能研究[D];山東大學;2011年

3 李鑫;電子束蒸發(fā)法制備摻雜氧化鋯薄膜[D];電子科技大學;2006年

4 王露;AFM的改進及其在材料學、生物學上的應用[D];重慶大學;2010年

，

本文編號：1853824