δ-Nb-Ti-N超导薄膜溶液法制备与超导性能研究
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摘要
采用化学溶液沉积法在Si衬底上生长立方结构的δ-Nb-Ti-N薄膜和δ-NbN薄膜,系统研究了掺杂前后薄膜颗粒度/晶粒度、微应力、N含量、载流子浓度及迁移率对超导转变温度、正常态电阻率和上临界场等的影响。得到如下结果:Ti组分的掺杂,使δ-Nb-Ti-N薄膜的晶格常数增大,晶粒尺寸减小,正常态电阻率升高,载流子浓度增大,超导转变温度T_C升高,根据BCS理论和GL方程进行综合分析,B_(C2)(0)由T_C、N和晶粒尺寸共同影响,总的结果为Ti组分的掺杂使B_(C2)(0)升高。
δ-Nb-Ti-N and δ-NbN thin films with cubic strcture were fabricated using chemical solution deposition in the study. The effects of particle size/grain size,microstrain,N content,electron carrier concentration and electron mobility on superconducting transition temperature,normal state resistivity and upper critical field before and after Ti doping were systematically investigated. The results showed that the lattice constant of the δ-Nb-Ti-N thin film is improved,the grain size decreases,the normal state resistivity increases,the N content,the carrier concentration increases,the superconducting transition temperature T_C increases. According to BCS theory and GL equation,the upper critical field B_(C2)( 0) is affected by T_C,N and grain size. The total result is that the doping of Ti component increases the upper critical field B_(C2)( 0).
δ-Nb-Ti-N and δ-NbN thin films with cubic strcture were fabricated using chemical solution deposition in the study. The effects of particle size/grain size,microstrain,N content,electron carrier concentration and electron mobility on superconducting transition temperature,normal state resistivity and upper critical field before and after Ti doping were systematically investigated. The results showed that the lattice constant of the δ-Nb-Ti-N thin film is improved,the grain size decreases,the normal state resistivity increases,the N content,the carrier concentration increases,the superconducting transition temperature T_C increases. According to BCS theory and GL equation,the upper critical field B_(C2)( 0) is affected by T_C,N and grain size. The total result is that the doping of Ti component increases the upper critical field B_(C2)( 0).
引文
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[3]TSETSERIS L,KALFAGIANNIS N,LOGOTHETIDIS S,et al.Role of N defects on thermally induced atomic-scale structural changes in transition-metal nitrides[J].Physical Review Letters,2007,99(12):125503.
[4]NINGTHOUJAM R S,GAJBHIYE N S.Synthesis,electron transport properties of transition metal nitrides and applications[J].Progress in Materials Science,2015,70:50-154.
[5]ZHANG L,PENG W,YOU L X,et al.Superconducting properties and chemical composition of Nb Ti N thin films with different thickness[J].Applied Physics Letters,2015,107(12):122603.
[6]SCHWARTZ R W.Chemical solution deposition of perovskite thin films[J].Chemistry of Materials,1997,9(11):2325-2340.
[7]ZOU G F,ZHAO J,LUO H M,et al.Polymer-assisted-deposition:A chemical solution route for a wide range of materials[J].Chemical Society Reviews,2013,42(2):439-449.
[8]HUI Z,TANG X,SHAO D,et al.Self-assembled c-axis oriented antiperovskite soft-magnetic Cu NCo3thin films by chemical solution deposition[J].Journal of Materials Chemistry C,2015,17(3):4438-4444.
[9]HUI Z,TANG X,SHAO D,et al.Epitaxial antiperovskite superconducting Cu NNi3thin films synthesized by chemical solution deposition[J].Chemical Communications,2014,50:12734-12737.
[10]张涵璐.金属氮化物超导薄膜溶液法制备、生长机理及性能研究[D].合肥:中国科学技术大学,2018.
[11]WERTHAMER N R,HELFAND E,HOHENBERG P C.Temperature and purity dependence of the superconducting critical field Hc2.III.electron spin and spin-orbit effects[J].Phys.Rev.,1966,147:295.