本文選題：鐵電體　切入點：光伏效應(yīng)　出處：《南京理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：鐵電體作為一種熱門的研究材料具有許多特殊的性質(zhì),如鐵電性、壓電性、熱釋電性、光伏效應(yīng)和阻變效應(yīng)。其中地,BiFeO_3是一種經(jīng)典的鐵電材料,其鐵電性、壓電性以及電疇反轉(zhuǎn)機制等已經(jīng)被廣泛研究。本文著重研究了 BiFeO_3薄膜的光伏效應(yīng),通過控制BiFeO_3材料的鐵電極化可以實現(xiàn)對其光伏效應(yīng)的調(diào)控,因此該材料未來有望應(yīng)用于光電傳感器領(lǐng)域。除此之外,隨著信息技術(shù)的快速發(fā)展,尋找可應(yīng)用于存儲器件的新材料也具有十分重要的意義。因此,本文在BiFeO_3材料的基礎(chǔ)上摻雜元素Cr形成了Bi_2FeCrO_6,一種較新穎的鐵電材料,并著重研究了 Bi_2FeCrO_6薄膜的阻變效應(yīng)。本文首先利用脈沖激光沉積系統(tǒng)制備高質(zhì)量的BiFeO_3和Bi_2FeCrO_6薄膜。然后,利用X射線衍射儀、原子力顯微鏡、Keithley數(shù)字源表、導(dǎo)電原子力顯微鏡和掃描隧道顯微鏡等儀器對所制備薄膜的表面形貌、微觀結(jié)構(gòu)、光伏效應(yīng)和阻變效應(yīng)進行了研究。本文包含以下三個方面的內(nèi)容:(1)高質(zhì)量BiFeO_3和Bi_2FeCrO_6外延單晶薄膜的制備;(2)BiFeO_3薄膜光伏效應(yīng)的研究;(3)Bi_2FeCrO_6薄膜阻變效應(yīng)的研究。具體內(nèi)容如下:首先,利用脈沖激光沉積系統(tǒng)在制備高質(zhì)量的BiFeO_3和Bi_2FeCrO_6薄膜。通過調(diào)控生長參數(shù),尋找到薄膜較優(yōu)的制備工藝窗口。利用原子力顯微鏡和X射線衍射儀分別對薄膜的表面形貌和微觀結(jié)構(gòu)進行表征,發(fā)現(xiàn)所制備的BiFeO_3和Bi_2FeCrO_6薄膜為表面納米級平整的單晶外延薄膜。然后,利用 Keithley 數(shù)字源表對 SrTiO_3/La_(0.7)Sr_(0.3)MnO_3/BiFeO_3/ITO(In_2O_3:SnO_2=9:l)結(jié)構(gòu)的光伏效應(yīng)進行測量,成功地在BiFeO_3薄膜中觀察到光伏效應(yīng)。并且,該光伏效應(yīng)具有以下特點:第一,短路電流和開路電壓的方向均隨著薄膜極化方向的反轉(zhuǎn)而改變;第二,短路電流的絕對值隨著光照強度以及薄膜極化強度的增加而增加;第三,隨著測量溫度從25 ℃上升到130 ℃,短路電流從180 nA上升到480 nA。最后,利用導(dǎo)電原子力顯微鏡和掃描隧道顯微鏡對SrTiO_3/SrRuO_3/Bi_2FeCrO_6結(jié)構(gòu)的阻變效應(yīng)進行測量,且測量所使用的探針直徑分別為100nm和1nm。利用導(dǎo)電原子力顯微鏡在薄膜中觀察到了穩(wěn)定的、具有良好重復(fù)性的雙邊阻變效應(yīng);利用掃描隧道顯微鏡在薄膜觀察到了穩(wěn)定的單邊阻變效應(yīng)。并且,Bi_2FeCrO_6薄膜中阻變效應(yīng)的開關(guān)比(薄膜中高、低阻值之比)數(shù)值均在15到122之間。總之,本文對BiFeO_3以及Bi_2FeCrO_6薄膜的鐵電性、光伏效應(yīng)和阻變效應(yīng)進行了較為詳盡的研究,該研究結(jié)果不僅對BiFeO_3和Bi_2FeCrO_6材料的進一步科學(xué)研究具有重要的意義,還對其在存儲器和光電器件等方面的應(yīng)用具有一定的指導(dǎo)作用。
[Abstract]:Ferroelectrics have many special properties, such as ferroelectrics, piezoelectric properties, pyroelectric properties, photovoltaic effects and resistance effects. Piezoelectric properties and domain reversal mechanisms have been widely studied. In this paper, the photovoltaic effect of BiFeO_3 thin films is studied, and the photovoltaic effect can be controlled by controlling the ferroelectrode of BiFeO_3 materials. In addition, with the rapid development of information technology, it is of great significance to find new materials that can be used in memory devices. In this paper, Bi _ 2FeCr _ O _ 6, a novel ferroelectric material, was formed by doping Cr on the basis of BiFeO_3 material, and the resistance effect of Bi_2FeCrO_6 thin film was studied. In this paper, high quality BiFeO_3 and Bi_2FeCrO_6 thin films were prepared by pulsed laser deposition system. Using X-ray diffractometer, atomic force microscope (AFM) and Keithley digital source table, conducting atomic force microscope (AFM) and scanning tunneling microscope (SEM), the surface morphology and microstructure of the films were studied. The photovoltaic effect and the resistance effect are studied. This paper includes three aspects: (1) preparation of high quality BiFeO_3 and Bi_2FeCrO_6 epitaxial single crystal thin films; Research on photovoltaic effect of Si ~ (2 +) Bi ~ (2 +) BiFeO _ (3) thin films. The specific contents are as follows: first, High quality BiFeO_3 and Bi_2FeCrO_6 thin films were prepared by pulsed laser deposition system. The surface morphology and microstructure of the films were characterized by atomic force microscope (AFM) and X-ray diffractometer (XRD). The BiFeO_3 and Bi_2FeCrO_6 thin films are found to be nanoscale monocrystalline epitaxial thin films on the surface. Then, the Keithley digital source meter is used to measure the photovoltaic effect of the structure of SrTiO3 / La _ (0. 7) / SrTiO _ (0.3) MNO _ (3 / BiFeO _ (3) / BiFeO _ (3) / T _ 2O _ (3) / in _ s _ 2O _ 3 / S _ 2O _ (9: 1)) structure, and the photovoltaic effect is observed successfully in the BiFeO_3 film. The characteristics of the photovoltaic effect are as follows: first, the direction of the short-circuit current and the open-circuit voltage change with the reversal of the polarization direction of the film, and second, the absolute value of the short-circuit current increases with the increase of the light intensity and the polarization intensity of the film. Thirdly, with the temperature rising from 25 鈩，

本文編號：1638287