硅酸盐学报2025，Vol.53Issue(9)：2469-2478,10.DOI:10.14062/j.issn.0454-5648.20250225
界面SiOx层对BiFeO3/Si异质结电学性能的影响
Electrical Properties of BiFeO3/Si Heterojunctions with SiOx Interface Layer
摘要
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.关键词
铁电/半导体异质结/铁酸铋薄膜/硅衬底/氧化硅/电荷迁移Key words
ferroelectric/semiconductor heterojunction/bismuth ferrite thin film/silicon substrate/silicon dioxide/charge migration分类
数理科学引用本文复制引用
肖泽宇,雷林,刘琳,胡雪莉,黄凤珍,吕笑梅..界面SiOx层对BiFeO3/Si异质结电学性能的影响[J].硅酸盐学报,2025,53(9):2469-2478,10.基金项目
国家重点研发计划(2022YFA1402903) （2022YFA1402903）
国家自然科学基金(52172116,62171214). （52172116,62171214）
