| 101 | 0 | 92 |
| 下载次数 | 被引频次 | 阅读次数 |
构建铁电/半导体异质结构是现代多功能电子器件的重要发展方向。利用溶胶–凝胶方法在不同温度预处理后的n-Si衬底上制备了BiFeO3薄膜。结果表明,衬底预处理使得样品电滞回线细化变形,同时光电流变弱。结合介电–温度谱以及截面高分辨透射电子显微镜等分析表明,衬底预处理后,n-Si表面的SiOx层厚度增加,削弱了BFO与n-Si之间的pn结界面接触势垒以及相应的分压,有利于BFO的极化开关。势垒的降低伴随着界面内建电场的减小,对光生载流子分离运动的驱动力减弱。通过揭示不同SiOx厚度对铁电/半导体异质结界面及电荷迁移的影响,可为基于Si衬底的铁电集成器件的设计提供重要参考。
Abstract：Introduction As electronic technology and integrated circuits advance rapidly, the functional demands of devices are increasingly elevated. Ferroelectric/semiconductor heterostructures are significant in applications including memory, sensing, and optoelectronic devices because they combine the best qualities of both ferroelectric and semiconductor materials. In recent years, the variety and refinement of the preparation process have led to the successful direct integration of ferroelectric materials with semiconductor silicon. Nevertheless, constructing ferroelectric/semiconductor heterostructures devoid of any interface layers, particularly on silicon substrates, is exceedingly challenging. Due to thermal diffusion, there is usually a SiOx layer at the interface, which subsequently affects device performance. However, systematic researches are urgently need regarding the effect of the interface layer on the potential barriers, ferroelectric polarization, and carrier transport. This work develops SiOx layers of varying thicknesses and densities on the n-Si surface, followed by the fabrication of bismuth ferrite(BiFeO3) films on the pretreated substrate. When the substrate pretreatment temperature rises, the SiOx layer progressively thickens, thereby altering the interface barrier, polarization switching, and the transport of photogenerated carriers. This study presents a novel concept for the creation of ferroelectric/semiconductor heterostructures featuring several interface contact types and electrical transport pathways. Methods Oxygen was introduced into the tube furnace, which was later heated to 400–1000 ℃. Once the temperature stabilizes, the(100) oriented n-Si substrate(resistivity of approximately 10 Ω·cm) is put into the furnace. After heating for 1 h, the substrate is directly removed from the tube furnace and allowed to cool in a room temperature environment. The raw materials Bi(NO3)3·5H2O and Fe(NO3)3·9H2O were dissolved in acetic acid and ethylene glycol methyl ether, respectively. Subsequently, these two solutions were mixed, stirred for 8 h, and filtered to obtain a BiFeO3 precursor solution at a concentration of 0.1 mol/L. The precursors were spin-coated onto the pretreated n-Si(100) substrate at 3500 r/min for 30 s and heated at 180 ℃ for 5 min. The spin-coating process was done three times to attain a film thickness of approximately 60 nm, afterwards, the samples were annealed in a nitrogen environment at 380 ℃ for 15 min, followed by 550 ℃ for 50 min, with a heating rate of 10 ℃/min. Results and discussion The n-Si substrate was pretreated at various temperatures in an oxygen environment. The cross-sectional high-resolution transmission electron microscopy indicates an increase in the thickness of the SiOx layer with increasing substrate pretreatment temperature. The dielectric measurements show that when the pretreatment temperature is above 600 ℃, the activation energy of the dielectric relaxation begins to decline, signifying a decrease in the oxygen vacancy content while the transition of the oxygen vacancies from divalent to monovalent. Subsequently, BiFeO3 films were fabricated on the pretreated substrate. X-ray diffraction studies demonstrated that all the BiFeO3 films exhibit R3c polycrystalline structure. After substrate pretreatment, the clamping phenomenon of the BiFeO3/n-Si hysteresis loop disappears. As the pretreatment temperature increases, the loop becomes slimmer, and the coercive voltage decreases. The reason is that the increased thickness of the SiOx layer hinders the carrier migration between BiFeO3 and the n-Si substrate. At temperatures below and above 700 ℃, the SiOx can be considered as a tunneling layer and a resistive layer, respectively. I–V curves show that the BiFeO3/n-Si samples still exhibit rectification effects, but the cut–off voltage under negative bias and the conduction current under positive bias both decrease, which is consistent with the weakening of the interface barrier and the decrease in conductivity. Although the photocurrent and on–off ratio generally decline with the increasing pretreatment temperature, the on–off ratio of the sample on 700 ℃ pretreated substrate increases abnormally, attributed to the increased conductivity associated with the aggregation of monovalent oxygen vacancies. Conclusions BiFeO3 films are grown on n-Si substrates pretreated at different temperatures. As the pretreatment temperature increases, the SiOx layer on the n-Si surface became thicker and denser, accompanied by a reduction in oxygen vacancies and a transition from divalent to monovalent. The hysteresis loops are no longer clamped, with the coercive voltage deceased, and both the cut-off voltage of the I–V curves and the on–off ratio of the photocurrent reduce. The primary explanation is that the SiOx layer reduces the pn junction barrier and the built-in electric field at the BiFeO3/n-Si interface, facilitating the polarization switching of BiFeO3 and the transport of photogenerated carriers. The accumulation of oxygen vacancies at a particular temperature can result in an anomalous rise in photocurrent.
[1]LI Y,YANG Y L,ZHAO H Z,et al.Nonvolatile memory device based on the ferroelectric metal/ferroelectric semiconductor junction[J].Nano Lett,2025,25(4):1680-1688.
[2]YU T Q,HE F C,ZHAO J H,et al.Hf0.5Zr0.5O2 based ferroelectric memristor with multilevel storage potential and artificial synaptic plasticity[J].Sci China Mater,2021,64(3):727-738.
[3]ZHANG Z,SHI L,WANG B,et al.Epitaxial growth of full-vd Wα-In2Se3/Mo S2 heterostructures for all-in-one sensing and memory-computing artificial visual system[J].Chin Chem Lett,2025,36(3):109687.
[4]HU Y Q,XU W,LIU N T,et al.Artificial optoelectronic synapses based on light-controllable ferroelectric semiconductor memristor[J].Adv Optical Mater,2024,12(14):2302887.
[5]LIM T,LEE J M,JANG J.Flexible temperature sensor with 2D In2Se3ferroelectric-semiconductor field effect transistor exhibiting record high sensitivity[J].Small,2025,21(12):2410853.
[6]ZHANG Y,ZHAO X Y,CHEN J X,et al.Self-polarized Ba Ti O3 for greatly enhanced performance of Zn O UV photodetector by regulating the distribution of electron concentration[J].Adv Funct Mater,2020,30(5):1907650.
[7]ZHANG Y J,SU H X,LI H,et al.Enhanced photovoltaic-pyroelectric coupled effect of Bi Fe O3/Au/Zn O heterostructures[J].Nano Energy,2021,85:105968.
[8]ZHANG Y Z,YANG L Y,ZHANG Y J,et al.Enhanced photovoltaic performances of La-doped bismuth ferrite/zinc oxide heterojunction by coupling piezo-phototronic effect and ferroelectricity[J].ACS Nano,2020,14(8):10723-10732.
[9]THANGAVEL S,PAZHAMALAI P,KRISHNAMOORTHY K,et al.Ferroelectric-semiconductor Ba Ti O3-Ag2O nanohybrid as an efficient piezo-photocatalytic material[J].Chemosphere,2022,292:133398.
[10]S?AWI?SKA J,DI SANTE D,VAROTTO S,et al.Fe/Ge Te(111)heterostructures as an avenue towards spintronics based on ferroelectric Rashba semiconductors[J].Phys Rev B,2019,99(7):075306.
[11]CAI R G,KASSA H G,HAOUARI R,et al.Organic ferroelectric/semiconducting nanowire hybrid layer for memory storage[J].Nanoscale,2016,8(11):5968-5976.
[12]DU J Y,XIE D G,ZHANG Q H,et al.A robust neuromorphic vision sensor with optical control of ferroelectric switching[J].Nano Energy,2021,89:106439.
[13]ZHU M S,ZHENG H W,ZHANG J,et al.Polarization dependent ferroelectric photovoltaic effects in BFTO/Cu O thin films[J].Appl Phys Lett,2017,111(3):032901.
[14]YU P P,WANG W W,ZHENG T X,et al.Pyro-phototronic effect-enhanced photocurrent of a self-powered photodetector based on Zn O nanofiber arrays/Ba Ti O3 films[J].ACS Appl Mater Interfaces,2023,15(39):46031-46040.
[15]ABEL S,ELTES F,ELLIOTT ORTMANN J,et al.Large Pockels effect in micro-and nanostructured barium titanate integrated on silicon[J].Nat Mater,2019,18(1):42-47.
[16]ABEL S,ST?FERLE T,MARCHIORI C,et al.A strong electro-optically active lead-free ferroelectric integrated on silicon[J].Nat Commun,2013,4:1671.
[17]LI Z P,GUO X,LU H B,et al.An epitaxial ferroelectric tunnel junction on silicon[J].Adv Mater,2014,26(42):7185-7189.
[18]MOALLA R,CUEFF S,PENUELAS J,et al.Large anisotropy of ferroelectric and pyroelectric properties in heteroepitaxial oxide layers[J].Sci Rep,2018,8(1):4332.
[19]JAMES A R,XI X X.Effects of buffer layer thickness and strain on the dielectric properties of epitaxial Sr Ti O3 thin films[J].J Appl Phys,2002,92(10):6149-6152.
[20]YOON J G,KIM K.Growth of highly textured Li Nb O3 thin film on Si with Mg O buffer layer through the sol-gel process[J].Appl Phys Lett,1996,68(18):2523-2525.
[21]TENNE D A,XI X X,LI Y L,et al.Absence of low-temperature phase transitions in epitaxial Ba Ti O3 thin films[J].Phys Rev B,2004,69(17):174101.
[22]HSU W Y,RAJ R.Mg O epitaxial thin films on (100) Ga As as a substrate for the growth of oriented Pb Ti O3[J].Appl Phys Lett,1992,60(25):3105-3107.
[23]JUN S,KIM Y S,LEE J,et al.Dielectric properties of strained (Ba,?Sr)Ti O3 thin films epitaxially grown on Si with thin yttria-stabilized zirconia buffer layer[J].Appl Phys Lett,2001,78(17):2542-2544.
[24]MINH D H,LOI N V,DUC N H,et al.Low-temperature PZT thin-film ferroelectric memories fabricated on Si O2/Si and glass substrates[J].JSci Adv Mater Devices,2016,1(1):75-79.
[25]KORMONDY K J,POPOFF Y,SOUSA M,et al.Microstructure and ferroelectricity of Ba Ti O3 thin films on Si for integrated photonics[J].Nanotechnology,2017,28(7):075706.
[26]CHERNIKOVA A,KOZODAEV M,MARKEEV A,et al.Ultrathin Hf0.5Zr0.5O2 ferroelectric films on Si[J].ACS Appl Mater Interfaces,2016,8(11):7232-7237.
[27]张林涛,任天令,刘理天,等.硅基PZT铁电薄膜的界面和表面研究[J].压电与声光,2000,22(5):316-318.ZHANG Lintao,REN Tianling,LIU Litian,et al.Piezoelectrics Acoustooptics,2000,22(5):316-318.
[28]ZHANG Q,REN T L,ZHANG L T,et al.Interface and surface characterization of lead zirconate titanate thin films grown by sol-gel method[J].Jpn J Appl Phys,2001,40(8R):5074.
[29]KIM S H,YU G T,PARK G H,et al.Interfacial engineering of a Mo/Hf0.3Zr0.7O2/Si capacitor using the direct scavenging effect of a thin Ti layer[J].Chem Commun,2021,57(93):12452-12455.
[30]DUAN J H,ZHAO S J,TIAN F B,et al.Trap generation in whole gate stacks of Fe FET with Ti N/Hf0.5Zr0.5O2/Si Ox/Si (MFIS) gate structure during endurance fatigue[J].IEEE Trans Electron Devices,2022,69(12):6547-6551.
[31]WANG J,NEATON J B,ZHENG H,et al.Epitaxial Bi Fe O3multiferroic thin film heterostructures[J].Science,2003,299(5613):1719-1722.
[32]GUO R,YOU L,ZHOU Y,et al.Non-volatile memory based on the ferroelectric photovoltaic effect[J].Nat Commun,2013,4:1990.
[33]YI H T,CHOI T,CHOI S G,et al.Mechanism of the switchable photovoltaic effect in ferroelectric Bi Fe O3[J].Adv Mater,2011,23(30):3403-3407.
[34]ZHAO R D,MA N,SONG K,et al.Boosting photocurrent via heating Bi Fe O3 materials for enhanced self-powered UV photodetectors[J].Adv Funct Mater,2020,30(6):1906232.
[35]UCHIDA H,UENO R,FUNAKUBO H,et al.Crystal structure and ferroelectric properties of rare-earth substituted Bi Fe O3 thin films[J].JAppl Phys,2006,100(1):014106.
[36]JI W,YAO K,LIANG Y C.Bulk photovoltaic effect at visible wavelength in epitaxial ferroelectric Bi Fe O3 thin films[J].Adv Mater,2010,22(15):1763-1766.
[37]CATALAN G,SCOTT J F.Physics and applications of bismuth ferrite[J].Adv Mater,2009,21(24):2463-2485.
[38]BISWAS P P,PAL S,SUBRAMANIAN V,et al.Polarization driven self-biased and enhanced UV-visible photodetector characteristics of ferroelectric thin film[J].J Phys D:Appl Phys,2020,53(27):275302.
[39]LAN S Y,YU C,SUN F,et al.Tuning piezoelectric driven photocatalysis by La-doped magnetic Bi Fe O3-based multiferroics for water purification[J].Nano Energy,2022,93:106792.
[40]LEI L,LIU L,LU X M,et al.Controllable distribution and reversible migration of charges in Bi Fe O3-based films on Si substrates[J].ACSAppl Mater Interfaces,2021,13(36):43787-43794.
[41]LEI L,LIU L,LU X M,et al.Broadband and high-sensitivity photodetector based on Bi Fe O3/Si heterojunction[J].Adv Optical Mater,2023,11(1):2201893.
[42]SHENG Z G,SUN Y P,ZHU X B,et al.Transport properties and backward diode-like behaviour in manganite-based p-i-n junctions[J].JPhys D:Appl Phys,2008,41(13):135008.
[43]YANG Z H,GAO P Q,SHENG J,et al.Principles of dopant-free electron-selective contacts based on tunnel oxide/low work-function metal stacks and their applications in heterojunction solar cells[J].Nano Energy,2018,46:133-140.
[44]PATTERSON A L.The scherrer formula for X-ray particle size determination[J].Phys Rev,1939,56(10):978-982.
[45]MIN K L,HUANG F Z,JIN Y M,et al.Control of oxygen vacancies and their kinetic behaviours via reversible oxygen loss in Bi Fe O3ceramics[J].J Phys D:Appl Phys,2015,48(44):445301.
[46]KE Q Q,KUMAR A,LOU X J,et al.Origin of the enhanced polarization in La and Mg co-substituted Bi Fe O3 thin film during the fatigue process[J].Appl Phys Lett,2012,100(4):042902.
[47]ZHAO M J,SUN Z T,ZHANG Z X,et al.Suppression of oxygen vacancy defects in s ALD-Zn O films annealed in different conditions[J].Materials,2020,13(18):3910.
[48]LIUYANG J X,WANG L,HE X H,et al.Effect of argon annealing treatment on photoelectric properties of GZO films deposited by atomic layer deposition[J].J Phys Chem C,2024,128(9):4086-4092.
[49]QU J S,LIU W,LIU R Z,et al.Evolution of oxygen vacancies in cerium dioxide at atomic scale under CO2 reduction[J].Chem Catal,2023,3(10):100759.
[50]EOM K,CHOI E,CHOI M,et al.Oxygen vacancy linear clustering in a perovskite oxide[J].J Phys Chem Lett,2017,8(15):3500-3505.
[51]李领伟,曹世勋,黎文峰,等.氧含量对Fe掺杂YBCO体系中载流子局域化与离子团簇效应的影响[J].物理学报,2005,54(8):3839-3844.LI Lingwei,CAO Shixun,LI Wenfeng,et al.Acta Phys Sin,2005,54(8):3839-3844.
[52]TANG K C,MENG A C,HUI F,et al.Distinguishing oxygen vacancy electromigration and conductive filament formation in Ti O2 resistance switching using liquid electrolyte contacts[J].Nano Lett,2017,17(7):4390-4399.
[53]LI S Q,DU J G,LU B J,et al.Gradual conductance modulation by defect reorganization in amorphous oxide memristors[J].Mater Horiz,2023,10(12):5643-5655.
[54]YILDIRIM H,PACHTER R.Mechanistic analysis of oxygen vacancy-driven conductive filament formation in resistive random access memory metal/Ni O/metal structures[J].ACS Appl Mater Interfaces,2018,10(11):9802-9816.
[55]LIU L,LEI L,LU X M,et al.Polarization switching in Bi0.8La0.2Fe O3films with ferroelectric/semiconductor heterojunctions[J].Appl Phys Lett,2021,118(16):162904.
[56]HUI S C,ZHOU X,ZHANG L M,et al.Constructing multiphase-induced interfacial polarization to surpass defect-induced polarization in multielement sulfide absorbers[J].Adv Sci,2024,11(6):e2307649.
基本信息:
DOI：10.14062/j.issn.0454-5648.20250225
中图分类号:TB383.2;TN384
引用信息:
[1]肖泽宇,雷林,刘琳,等.界面SiO_x层对BiFeO_3/Si异质结电学性能的影响[J].硅酸盐学报,2025,53(09):2469-2478.DOI:10.14062/j.issn.0454-5648.20250225.
基金信息:
国家重点研发计划(2022YFA1402903); 国家自然科学基金(52172116,62171214)