本文選題：鈣鈦礦鈷氧化物 + 異質結��； 參考：《西安科技大學》2016年碩士論文

【摘要】：本文采用脈沖沉積技術(PLD)分別在n型0.7wt%Nb-SrTiO3(100)基片上制備(La_(1-x)Pr_x)_(0.7)Sr0.3CoO3(x=0,0.2,0.4,0.6,0.8)和La_(0.82)Sr_(0.18)Co_(1-x)Cr_xO_3(x=0,0.2,0.4,0.6,0.8,1.0)系列異質結。通過X射線衍射(XRD)、原子力顯微鏡(AFM)、低溫測試系統(tǒng)和光電測試系統(tǒng)對制備的異質結的晶體結構、表面形貌、輸運特性和光伏特性進行了表征及研究分析。主要結論如下:1.XRD和AFM測試表明系列異質結樣品均呈現出良好的外延生長特性,薄膜沿著基底晶向擇優(yōu)生長,樣品表面顆粒致密均勻,起伏度較小,生長質量良好。通過橢圓偏振光譜儀測得異質結的薄膜厚度范圍為90-110 nm。2.對于(La_(1-x)Pr_x)_(0.7)Sr_(0.3)CoO_3/Nb-SrTiO_3系列異質結,Pr離子的摻入導致材料的晶格結構發(fā)生改變,各異質結由于薄膜與基底晶格的失配度不同而表現出不同的輸運特性。隨著溫度的增加,結間勢壘降低,耗盡層變窄,異質結的整流特性減弱。3.在激光的照射下,(La_(1-x)Pr_x)_(0.7)Sr_(0.3)CoO_3/Nb-SrTiO_3系列異質結樣品中可以測試到持續(xù)的光電壓,在473 nm激光照射下的光電壓高于532 nm激光照射下的光電壓,x=0.8的異質結樣品的光電壓最大值隨著溫度升高而降低。對光生電壓上升沿和下降沿擬合后發(fā)現下降時間常數即非平衡載流子的壽命在較大的ms量級且隨溫度的升高而減小。4.在La_(0.82)Sr_(0.18)Co_(1-x)Cr_xO_3/Nb-SrTiO3系列異質結中,Cr離子摻雜量比較低的異質結樣品具有很好地整流性,當摻雜比例較高時界面漏電機制主要為歐姆導電,主要是由于Cr離子與Co離子之間發(fā)生電子躍遷使得材料中的載流子濃度增加。5.激光的照射下,在x=0和x=0.4的La_(0.82)Sr_(0.18)Co_(1-x)Cr_xO_3/Nb-SrTiO3樣品中觀察到持續(xù)光電壓的產生,473 nm激光照射下的光電壓高于532 nm激光照射下的光電壓,x=0的異質結樣品的光電壓最大值隨溫度的升高先升高后降低,通過對光生電壓下降沿的指數函數擬合后發(fā)現非平衡載流子壽命的下降時間常數隨溫度升高而減小,且低溫下具有較大的值,在改善光伏器件性能方面具有比較重要的研究意義。
[Abstract]:A series of heterojunctions have been prepared by pulse deposition technique (PLD) on n type Nb-SrTiO3O _ (100) substrates, respectively. A series of heterostructures have been prepared on n type Nb-SrTiO3O _ (100) substrates. The crystal structure, surface morphology, transport and photovoltaic properties of the heterojunction were characterized and analyzed by X-ray diffraction (XRD), atomic force microscope (AFM), low temperature measurement system and photoelectric measurement system. The main conclusions are as follows: 1. XRD and AFM measurements show that the heterojunction samples exhibit good epitaxial growth characteristics. The films grow in preferential direction along the substrate crystal direction. The surface particles of the films are compact and uniform, the fluctuation is small, and the growth quality is good. The thickness range of heterojunction films measured by elliptical polarization spectrometer is 90-110nm.2. The doping of pr ions in the Nb-SrTiO3 series heterojunction leads to the change of the lattice structure of the material. The heterostructures show different transport characteristics due to the mismatch between the thin films and the substrate lattice, because of the difference in the mismatch between the thin films and the substrate lattices. With the increase of temperature, the interjunction barrier decreases, the depletion layer becomes narrower, and the rectifying characteristic of heterojunction weakens by .3. The persistent photovoltage can be measured in the Lasta1-xSrTiO3 series heterojunction samples. The maximum photovoltage of the heterojunction samples with 473 nm laser irradiation is higher than that with 532 nm laser irradiation x 0.8 heterojunction sample. The maximum photovoltage of the heterojunction sample with 0.3s / s CoO3 / Nb-SrTiO3 heterojunction can be decreased with the increase of the temperature, and the photovoltage of the heterojunction sample with the laser irradiation of 473 nm is higher than that of the heterojunction sample with the laser irradiation of 532nm, and the maximum of the photovoltage of the heterojunction sample is decreased with the increase of temperature. After fitting the rising edge and descending edge of photogenerated voltage, it is found that the decreasing time constant, that is, the lifetime of the non-equilibrium carrier is in the larger Ms order and decreases with the increase of temperature. In La_(0.82)Sr_(0.18)Co_(1-x)Cr_xO_3/Nb-SrTiO3 series heterojunction samples with low doping amount of Cr ion have good rectifying property. The main mechanism of interface leakage is ohmic conduction when doping ratio is high. It is mainly due to the electron transition between Cr ion and Co ion that the carrier concentration in the material increases by .5. Under laser irradiation, It was observed that the maximum photovoltage of heterojunction samples exposed to 473 nm laser was higher than that of heterojunction sample with 532nm laser irradiation. The maximum photovoltage of heterojunction samples increased first and then decreased with the increase of temperature. By fitting the exponential function of the drop edge of photogenerated voltage, it is found that the decreasing time constant of non-equilibrium carrier lifetime decreases with the increase of temperature, and has a large value at low temperature. In improving the performance of photovoltaic devices has more important research significance.
【學位授予單位】：西安科技大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：O611.4

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