發(fā)布時(shí)間：2018-04-09 13:46

  本文選題：LiNbO_3　切入點(diǎn)：Ge_2Sb_2Te_5　出處：《南京大學(xué)》2013年碩士論文

【摘要】：隨著閃存在讀取速度、尺寸大小和功耗上局限性的逐漸突顯,尋找一種閃存替代技術(shù)成為了各大電子行業(yè)巨頭研究的重要方向。目前最主要的四種閃存替代技術(shù)分別是鐵電隨機(jī)存儲(chǔ)器、磁阻隨機(jī)存儲(chǔ)器、相變隨機(jī)存儲(chǔ)器和阻變隨機(jī)存儲(chǔ)器。本論文主要研究了兩種信息存儲(chǔ)材料,一種是鈮酸鋰(LiNbO3)單晶,它是典型的鐵電材料,可以用于光電調(diào)制、倍頻、光參量振蕩、以及全息記錄等。另一種是鍺銻碲(Ge2Sb2Te5)合金薄膜,它是相變存儲(chǔ)材料,可以用于非易失性存儲(chǔ)器。 本論文研究主要針對(duì)關(guān)系到這兩種材料的實(shí)際應(yīng)用的核心基礎(chǔ)問(wèn)題展開(kāi),即鈮酸鋰中鐵電疇的生長(zhǎng)和弛豫問(wèn)題,以及鍺銻碲中的非晶-晶態(tài)相變問(wèn)題,分別研究了它們對(duì)外電場(chǎng)和外應(yīng)力場(chǎng)的響應(yīng)情況。主要?jiǎng)?chuàng)新成果如下： 1.利用掃描探針顯微鏡研究了外電場(chǎng)下近化學(xué)計(jì)量比鈮酸鋰單晶中鐵電疇的生長(zhǎng)和弛豫特性。 對(duì)于掃描極化方式制備的條形疇,我們發(fā)現(xiàn),疇區(qū)生長(zhǎng)的平均初始寬度隨著極化電壓的增加而線性增加,隨著掃描速率的增加而指數(shù)衰減；疇區(qū)的弛豫隨初始寬度的減小呈現(xiàn)穩(wěn)定無(wú)弛豫、長(zhǎng)度縮減、及完全消失這三種狀態(tài),臨界穩(wěn)定初始寬度隨晶片厚度指數(shù)增長(zhǎng)；為保持相鄰條形疇區(qū)獨(dú)立不相融合的狀態(tài),其間距應(yīng)大于條形疇的寬度；沿鈮酸鋰不同晶向極化的條形疇在生長(zhǎng)形態(tài)、寬度和粗糙度方面有差異。 對(duì)于定點(diǎn)脈沖極化的疇區(qū),我們發(fā)現(xiàn),根據(jù)疇區(qū)中心出現(xiàn)的與外電場(chǎng)反向的異常翻轉(zhuǎn)區(qū)大小的不同,對(duì)應(yīng)有兩類不同的相鄰疇區(qū)間相互作用。對(duì)于中心異常翻轉(zhuǎn)區(qū)較小的準(zhǔn)實(shí)心疇區(qū),鄰近區(qū)域的再次極化會(huì)使先極化疇區(qū)的中心異常翻轉(zhuǎn)區(qū)消失,疇區(qū)沿外場(chǎng)方向進(jìn)一步生長(zhǎng)；而對(duì)于中心異常翻轉(zhuǎn)區(qū)較大的非完整環(huán)形疇區(qū),鄰近區(qū)域的再次極化則會(huì)加速先極化疇區(qū)的弛豫消失過(guò)程。這兩種不同的影響可能源于疇構(gòu)型的差異。 2.利用脈沖激光沉積系統(tǒng)制備了非晶態(tài)的Ge2Sb2Te5薄膜,并研究了外加機(jī)械應(yīng)力對(duì)其升溫晶化行為的影響。發(fā)現(xiàn),張應(yīng)力使得晶化溫度降低,而壓應(yīng)力使得晶化溫度升高。隨應(yīng)力從壓應(yīng)力變化到張應(yīng)力(張、壓應(yīng)力分別以正、負(fù)應(yīng)力值表示),晶化溫度近似線性下降。實(shí)驗(yàn)中,我們還觀察到由應(yīng)力大小不均勻?qū)е碌木Щ瘻囟鹊恼箤挰F(xiàn)象。
[Abstract]:This paper mainly studies two kinds of information storage materials , such as ferroelectric random access memory , magnetoresistive random access memory , phase change random access memory and random access random access memory . The main four kinds of flash memory replacement technologies are ferroelectric random access memory , magnetoresistive random access memory , phase change random access memory and random access random access memory . The paper mainly studies two kinds of information storage materials , one is lithium niobate ( LiNbO 3 ) single crystal , it is a typical ferroelectric material , it can be used for photoelectric modulation , frequency doubling , optical parametric oscillation , and holographic recording . The other is Ge2Sb2Te5 alloy thin film , it is phase change storage material , can be used in non - volatile memory .

This paper mainly focuses on the core basic problem of the practical application of the two materials , namely , the growth and relaxation of the ferroelectric domains of lithium niobate and the amorphous - crystalline phase transition in the germanium - antimony tellurium , and the responses of their external electric field and external stress field are studied respectively . The main innovations are as follows :

1 . The growth and relaxation properties of the ferroelectric domains in the lithium niobate single crystal under the external electric field were investigated by using a scanning probe microscope .

For the stripe domains prepared by scanning polarization , we find that the average initial width of the domain grows linearly with the increase of the polarization voltage , and decreases exponentially with the increase of the scanning rate ;
The relaxation of the domain region decreases with the decrease of the initial width . The critical stable initial width increases with the thickness of the wafer .
in ord to maintain that state of independent non - phase fusion of adjacent strip domain regions , the spacing should be greater than the width of the stripe domain ;
The stripe domains of different crystal orientations of lithium niobate differ in growth morphology , width and roughness .

For the domain region of fixed - point pulse polarization , we found that there are two different kinds of adjacent domain - interval interactions , depending on the size of the abnormal inversion region opposite to the external electric field in the domain center .
For a large non - complete circular domain region of the central abnormal inversion region , the re - polarization of the adjacent region accelerates the relaxation disappearance process of the first polarized domain region .

2 . The amorphous Ge2Sb2Te5 thin film was prepared by pulsed laser deposition system . The influence of applied mechanical stress on the crystallization behavior was studied . It was found that tensile stress caused the crystallization temperature to decrease . The compressive stress caused the crystallization temperature to increase . As the stress changed from the compressive stress to the tensile stress , the crystallization temperature was approximately linearly decreased . In the experiment , we also observed the broadening of crystallization temperature caused by the nonuniform stress magnitude .

【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TP333;O484.4

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 唐亞陸;杜澤民;;脈沖激光沉積(PLD)原理及其應(yīng)用[J];桂林電子工業(yè)學(xué)院學(xué)報(bào);2006年01期

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本文編號(hào)：1726682