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Fabrication of Nanopillar structure by self-assembly growth

Fabrication of Nanopillar structure by self-assembly growth. Tanaka Lab Sakamoto Takuya. Contents. Back ground spintronics Nano structure with one-dimensional electrical pass nanopillar structure Epitaxial growth by pulsed laser deposition

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Fabrication of Nanopillar structure by self-assembly growth

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  1. Fabrication of Nanopillar structure by self-assembly growth Tanaka Lab Sakamoto Takuya

  2. Contents • Back ground spintronics Nano structure with one-dimensional electrical pass nanopillar structure Epitaxial growth by pulsed laser deposition Fabrication method by self-assembly growth • Results and discussion of my research • Summary

  3. Spintronics Electronics Magnetics spin charge e- Spin and charge (Fe,Zn)3O4/Pb(Zr,Ti)O3 spintronics Ferromagnetic semiconductor Magnetism depends on carrier concentration e- e- e- e- e- e- e- Ｅ ferroelectrics Modulation of magnetism by electric field Spontaneous electric polarization Functional oxide is attractive !! 田中秀和等, 機能材料28 54 (2008)

  4. Nano structure with one-dimensional electrical pass (La,Pr,Ca)MnO3 (Fe,Mn)3O4 Y Goto et al Nano. Lett9 1962 (2009) Y Yanagisawa et al Appl. Phys. Lett89 253121 (2006) Nano structureswith one-dimensional electrical pass have beneficial properties which bulk materials never possess

  5. Nanopillar structure Ferromagnetic semiconductor one-dimensional electrical pass ⇒　sharp metal insulator transition ferroelectrics ～100nm Surrounding interfaces between ferroelectrics and ferromagnetic semiconductor ⇒ the efficiency of magnetic modulation could drastically enhance How to make this structure? It is difficult to make this structure by using conventional lithography techniques

  6. Epitaxial growth by pulsed laser deposition Pulsed laser deposition Epitaxial growth substrate By using pulsed laser deposition, we can gain high quality epitaxial thin films.

  7. Fabrication method by self assembly growth Mixed target Pulsed laser deposition Mixed target Grown vertically on a substrate nucleation spinel perovskite Under certain condition Discussion of difference of Wetting condition HaimeiZheng et.al, Nano.Lett6 1401(2006)

  8. Purpose and detail condition of my research （１）Purpose Fabrication of BiFeO3-(Fe,Zn)3O4nanopillar structure by self-assembly growth （２）detail condition target ：(BiFeO3)0.65(Fe2.2Zn0.8O4)0.35 substrate：SrTiO3(100) (111) (110) substrate temperature ：400℃～800℃ Oxygen pressure：0.01Pa～10Pa （３）evaluation method X-ray diffraction(θ-2θ)atomic force microscope(AFM) Scanning Electron Microscope(SEM) Energy Dispersive X-ray spectroscopy(EDX) ferroelectrics Ferromagnetic semiconductor

  9. Growth condition Optimized condition Optimized condition amorphous region Measurement point ● Crystal region amorphous region Two crystal phases (spinel, perovskite) were successfully separated.

  10. Surface structure and size diagram １μm average131nm Rectangular shaped nanopillar structures were obtained.

  11. EDX(Energy Dispersive x-ray Spectroscopy) measurement SEM image １μm Bi mapping image This result indicate BiFeO3nanopillars embedded in (Fe,Zn)3O4 matrix １μm

  12. Crystal growth orientation Lattice constant STO: a = 3.90Åcubic [100] FZO: a = 8.39Å cubic [010] BFO: a = 3.95Å c/a = 1.016 tetragonal STO,BFO direction [100] [010] Lattice mismach FZO direction STO[100] // BFO[100]0.77% STO[100] // FZO[110]1.28% SEM image indicates growth direction: BFO[100]// FZO[110] STO[100] // FZO[100]7.03%

  13. Structure density control STO (100) [100] [100] 2μm 2μm [010] [010] STOdirection STOdirection BFO:FZO BFO:FZO 65:35 35:65 density of nano pillars were changed by volume fraction of target.

  14. BFO Structure morphology control FZO STO (001) STO (111) STO (110) 1μm 500nm 500nm FZO (111)plane (110)plane (001)plane Nano pillar structures were obtained on STO(001) (111) (110) substrates and pillar shapes were changed by substrate direction.

  15. Summery • We suggest nanopillar structure can be used as a spintronic device because it has nano one-dimensional channel and surrounding interfaces between ferroelectrics and ferromagnetic semiconductor. • In my research, nano-pillar structures were successfully obtained and by changing volume fraction and substrate orientation, the structures were controlled. • The next charenge is pillar-matrix control. Future work

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