BIT/ST/LSCO/MgO Variations of Microstructures and Electrical Properties of BIT/ST/LSCO/MgO Epitaxial Films by Annealing 2003 2
BIT/ST/LSCO/MgO Variations of Microstructures and Electrical Properties of BIT/ST/LSCO/MgO Epitaxial Films by Annealing 2003 2
2003 2
Application Ferroelectric properties Ferroelectric material FRAM fatigue, imprint, retention, aging Pb-Family, SrBi 2 Ta 2 O 9, BaTiO 3, Bi 4-x La x Ti 3 O 12, YMnO 3, Bi 4 Ti 3 O 12 DRAM Infrared sensor Dieletric constant, Leakage current Piezoelectric coefficient SrTiO 3, Ba 1-x Sr x TiO 3, PbTiO 3 PZT, PbTiO 3, Pb 1-x La x (Zr y Ti 1-y ) 1-0.25x O 3 SAW filter SAW velocity LiNbO 3, LiTaO 3 Microwave device Electro-optic device Dieletric loss, Electro-optic coefficient Electro-optic coefficient, Band gap Ba 1-x Sr x TiO 3 BaTiO 3, KNbO 3, Pb 1-x La x (Zr y Ti 1-y ) 1-0.25x O 3
0 0 6 BIT FWHM : 1.23 90 degree 0 100 200 300 400 Phi ( φ )
Intensity (arb. unit ) 0 0 4 BIT 0 0 6 BIT 0 0 8 BIT 0 0 1 LSCO 0 0 1 ST 0 0 10 BIT 0 0 12 BIT 0 0 14 BIT 0 0 2 MgO 0 0 16 BIT 0 0 2 ST 0 0 2 LSCO 0 0 18 BIT (f) (e) (d) (c) (b) (a) 0 10 20 30 40 50 60 70 Diffraction angle ( 2q )
E 2 E 1 88nm A 1 114nm 81nm LSCO ST epoxy BIT A 1 Volatilization of Bi (Thickness 4nm) ST A 2 MgO substrate 0016 BIT // 001 ST BIT 100nm 110 BIT // 010 ST 5nm 110 BIT // 010 ST 0016 BIT // 001 ST 11.8Å 12Å 3.4Å 13.1Å 3.5Å 3.53Å 13.3Å 13.3Å 13.4Å 2nm
Volatilization of Bi (Thickness 20nm) A 1 A 1 epoxy A 2 BIT BIT E 1 83nm E 2 ST LSCO 100nm ST MgO substrate 95nm 84nm 0016 BIT // 001 ST ST 110 BIT // 010 ST 14.56Å 14.5Å 14.3Å 14.2Å 2nm 0016 BIT // 001 ST 3.6Å 3.7Å 110 BIT // 010 ST 2nm 3.5Å
Volatilization of Bi (Thickness 24nm) 75nm A 1 epoxy A 2 BIT 133nm BIT 104nm ST A 1 LSCO E 1 E 2 ST 0016 BIT // 001 ST MgO substrate 100nm 110 BIT // 010 ST 5nm P 1 zone 5.16Å BIT BIT BIT P 2 zone 7.26 Å BIT 0016 BIT // 001 ST 2nm 110 BIT // 010 ST
71nm 107nm 94nm ST LSCO MgO substrate A 1 BIT 0016 BIT // 001 ST A 1 E 1 E 2 A 2 ST Volatilization of Bi (Thickness 21nm) 100nm 110 BIT // 010 ST 2nm BIT 110 BIT // 010 ST 0016 BIT // 001 ST 1nm
110 BIT // 010 ST 0016 BIT // 001 ST 81nm 117nm 94nm BIT D 1 epoxy A 2 A 1 MgO substrate epoxy A 1 100nm BIT ST LSCO E 1 E2 Volatilization of Bi (Thickness 11nm) 5nm ST 14.6Å 14.6Å 14.6Å 13.9Å 13.2Å D 2 0016 BIT // 001 ST 2nm 110 BIT // 010 ST
MgO substrate 110 BIT // 010 ST 0016 BIT // 001 ST LSCO ST BIT E 2 E 1 A 2 ST A 1 87nm 110nm A 1 71nm BIT epoxy Volatilization of Bi (Thickness 8nm) 100nm 5nm 0016 BIT // 001 ST 110 BIT // 010 ST 3.57Å 3.51Å 3.51Å 14.74Å 14.74Å 14.35Å 1nm
Å Å Å Å Å Å.
Bi SrO, rock saltlike layer Sr Bi
2 2 lattice misfit : ä a BIT or b BIT 2 a ST δ b b = BIT 2a 2a ST ST BIT ST c 8c δ c c = BIT 8c ST 8c ST
ST 002 ST 020 020 220 002 0016 220 0016 Z ST [ 1 0 0 ] ST 020 Z ST [ 1 0 0 ] ST 002 220 002 020 0016 0016 220 Z ST [ 1 0 0 ] Z ST [ 1 0 0 ] ST 020 002 220 ST 002 020 0016 0016 220 Z ST [ 1 0 0 ] Z ST [ 1 0 0 ]
BIT b / 2 = b ST Perovskite unit (Bi 2 O 2 ) 2 + layer Perovskite unit c BIT =8c ST (Bi 2 O 2 ) 2 + layer Perovskite unit c BIT Bi Oxygen b BIT 110 BIT // 010 ST b BIT a ST a BIT b ST Sr Oxygen
-0.285-0.8685 d BIT c d BIT b -0.286-0.287-0.288 Lattice misfit ( d ) -0.8690-0.8695-0.8700-0.8705-0.289-0.290-0.291-0.292-0.293-0.294-0.295-0.296-0.297-0.298-0.299-0.8710 0 10 20 30 40 Annealing time ( min ) 50 60-0.300
Bi 2O 2 layer O Bi layer by Localized Sr Insertion rock salt like Bi SrO, rock salt Bi Bi 2O 2 layer Substitution of Bi by Sr Bi 2O 2 layer Sr/Bi Sr/Bi Bi 2O 2 layer
(a) E 1 E 2 Sr L Sr L Bi L Bi L Bi L Bi L Sr L Bi L (b) E 1 E 2 (c) E 1 E 2 (d) E 1 E 2 (e) E 1 E 2 (f) E 1 E 2
Sr in BIT ( Atomic% ) 22 20 18 16 14 12 10 8 6 4 2 0-2 -4 Sr in BIT Bi in ST 0 10 20 30 40 50 60 Annealing time ( min ) 22 20 18 16 14 12 10 8 6 4 2 0-2 -4 Bi in ST ( Atomic% )
ST ST
Dielectric constant Dielectric loss 440 420 400 380 360 340 320 300 280 0.80 0.75 0.70 0.65 0.60 0.55 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00-0.05 (f) (e) (d) (c) (b) (a) Frequency [ khz ] 1 10 100 1000 1 10 100 1000 Frequency [ khz ] (f) (e) (d) (c) (b) (a)
Relative dielectric constant( 1 / e r ) 0.0042 0.0040 0.0038 0.0036 0.0034 0.0032 e r =241.62 C = A * X + B Parameter Value Error -------------------------------------------------- B 0.00502 2.96884E-4 A -0.00329 7.63903E-4 e r =256.87 -------------------------------------------------- e r =301.52 0.25 0.30 0.35 0.40 0.45 0.50 Volume fraction of ST phase
440 420 Dielectric constant 400 380 360 340 320 300 280 260 Measured at 100kHz Calculated from eq(1) 240 0 10 20 30 40 Annealing time ( min ) 60
16 14 12 10 8 6 4 2 0-2 -4-6 -8-10 -12-14 -16 20 15 10 6V 8V 10V 12V 14V 16V 6V 8V 10V 12V 14V 16V 5 0-5 -10-15 -20 6V 8V 10V 12V 14V 16V 6V 8V 10V 12V 14V 16V 18 16 14 12 10 8 6 4 2 0-2 -4-6 -8-10 -12-14 -16-18 6V 8V 10V 12V 14V 16V -700-600-500-400-300-200-100 0 100 200 300 400 500 600 700-700-600-500-400-300-200-100 0 100 200 300 400 500 600 700 6V 8V 10V 12V 14V 16V
Pr [ ìc / cm 2 ] Ec [ kv / cm ] as-prepared 0.1 14 10min 0.7 28 20min 0.8 33 30min 1.4 59 40min 1.2 55 1hr 1.7 69
2 2