镁和钾交替掺杂BST薄膜优化设计与介电特性研究
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摘要
根据K掺杂BST(KBST)和Mg掺杂BST(MBST)薄膜的优点,设计K和Mg三明治交替掺杂BST薄膜KBST/MBST/KBST(K/M/K)和MBST/KBST/MBST(M/K/M),用溶胶-凝胶(sol-gel)法在Si/SiO_2/Ti/Pt基片上制备该薄膜,研究其介电特性。薄膜为立方钙钛矿结构,平均晶粒尺寸16~20 nm。交替掺杂有效整合K掺杂和Mg掺杂,为受主掺杂,晶格常数增大。K/M/K掺杂显著增强晶化、促进薄膜生长,M/K/M掺杂明显细化晶粒、改善界面特性。20 V下C-V测试表明,KBST、MBST、M/K/M型及K/M/K型薄膜的最大电容依次为91、38、37和47 pF,调谐率64%、27%、38%和42%及介电损耗2.90%、1.67%、1.33%和1.58%;随膜厚增加,三者减小,调谐率与损耗之比值增大。M/K/M型薄膜具有最佳综合介电性能,可满足微波调谐需要。对有关机理进行了讨论。
K and Mg alternately doped BST films have been designed as KBST/MBST/KBST/MBST/KBST(K/M/K) and MBST/KBST/MBST/KBST/MBST(M/K/M) and prepared by a sol-gel method, and the dielectric properties have been studied. Two films show cubic perovskite structures, acceptor doping and increased lattice parameter with average grain sizes of 16~20 nm. M/K/M alternate doping is excellent at refining grains, improving interfaces and making film dense, whereas KMK doping is excellent at enhancing crystallization and promoting film growing. C-V measurement at 100 k Hz and-20~20 V shows M/K/M-BST and K/M/K-BST films orderly exhibit maximum capacitances of 37 and 47 p F, tunability of 38% and 42% and dielectric losses of 1.3% and 1.6%, respectively. Increasing film thickness makes the capacitance, tunability and dielectric loss decrease but makes the ratio of tunability/dielectric loss increase. M/K/M-BST film exhibits better combination of dielectric properties, meeting the needs of tunable microwave applications. Related mechanisms were discussed and K or Mg doped BST film was compared.
K and Mg alternately doped BST films have been designed as KBST/MBST/KBST/MBST/KBST(K/M/K) and MBST/KBST/MBST/KBST/MBST(M/K/M) and prepared by a sol-gel method, and the dielectric properties have been studied. Two films show cubic perovskite structures, acceptor doping and increased lattice parameter with average grain sizes of 16~20 nm. M/K/M alternate doping is excellent at refining grains, improving interfaces and making film dense, whereas KMK doping is excellent at enhancing crystallization and promoting film growing. C-V measurement at 100 k Hz and-20~20 V shows M/K/M-BST and K/M/K-BST films orderly exhibit maximum capacitances of 37 and 47 p F, tunability of 38% and 42% and dielectric losses of 1.3% and 1.6%, respectively. Increasing film thickness makes the capacitance, tunability and dielectric loss decrease but makes the ratio of tunability/dielectric loss increase. M/K/M-BST film exhibits better combination of dielectric properties, meeting the needs of tunable microwave applications. Related mechanisms were discussed and K or Mg doped BST film was compared.
引文
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[3]Cole M W,Joshi P C,Ervin M H et al.Thin Solid Films[J],2000,374:34
[4]Sun X H,Zhu B L,Liu T et al.J Appl Phy[J],2006,99:084103
[5]Liao J X,Wei X B,Xu Z Q et al.Vacuum[J],2014,107:291
[6]Wang Z Y,Liu J S,Ren T L et al.Chin J Semi[J],2002,23(8):830
[7]Liao J X,Wei X B,Pan X F et al.J Inorg Mater[J],2009,24:962
[8]Tkach A,Vilarinho P M,Kholkin A L.Acta Materialia[J],2005,53:5061