Understanding Interface Formation Interactions Between BTO/MgO ...
Undergraduate/Graduate Category: Engineering and Technology Degree Level: PhD, BS Abstract ID# 208
Understanding Interface Formation Interactions Between BTO/MgO/SiC By Epitaxial Growth of BaTiO3 Thin Film On SiC (0001) Negar 1Northeastern
Zhuhua
2 Cai ,
Emma
1 Kaeli ,
RESULTS
METHOD
INTRODUCTION Interface Engineering of Functional Oxide Multilayer Heterostructures to Enable Next-Generation Electronic Devices
Piezoelectric (PZT) Ferroelectric( BTO)
Wide Band Gap Semiconductor (SiC)
Cleaning Method - 6H-SiC substrates cleaned in ex-situ hydrogen furnace
20
- 330-370, C0=(A/d)*ε0
270 K Orthorhombic
300 K Tetragonal
40
45
50
55
•Surface polarization shows switching by EFM
1. Cleaned 6h-Sic (0001) Substrate - smooth, stepped surface with a √3×√3 R30 surface reconstruction
RMS: 0.43 nm
SiC (0001) √3×√3 R30°
200nm
•Impact of voltage change measureable but…
MgO(111)
SiC(0001)
MgO (111) (1x1)-OH
TiO2 Ti 2p
3. BaTiO3 Growth on MgO/SiC by MBE Finding optimum flux for Ti by holding barium flux, oxygen species, and substrate temperature (650 oC) constant - Growth Conditions: Time - 30 min Temperature - 680 oC Ba flux = 1.0×1014 #/cm2 sec Ti current - 45, 43, 41, 40.5 A Pressure - 5.0×10-6 Torr Excess titanium promotes TiO oxidation state
The engineered MgO template is both effective and necessary to promote the heteroepitaxy of BTO
Min: 765Max: 655Max: 4826 684Max: 700Max: 4155 4776 5569
400 K Cubic
• BTO, thin films consisting of poly crystalline BTO tend to stabilize cubic symmetry! Challenges: •Crystalline structure control •Stoichiometry control •Plane alignment •Effective integration with hetero substrate
good tools….
35
CONCLUSION
Tuomas H. E. et all, March 4, 2013
Molecular Beam Epitaxy and Ultra-high Vacuum
30
RESULTS
200nm
170K Rhombohedral
25
2 theta
Pink: Ti4+ Blue: Ba2+ Red: O2+
- for BTO [111] d33, f= 124 pm V-1 and BTO [001] d33, f= 35 pm V-1
BTO(111)
6H-SiC(0007) 6H-SiC(0008)
RMS: 0.45 nm
BaTiO3 (BTO): • Perovskite Ferroelectric • Strong piezoelectric effect
6H-SiC(0006)
Analysis - In-Situ: X-Ray Photoelectron Spectroscopy (Orange), Reflection High-Energy Electron Diffraction (Blue) - Ex-Situ: Field Emission SEM ,Scanning Force Microscopy (AFM, MFM, EFM)
2. MgO Growth on 6H-SiC by MBE - Growth Conditions: Time – 10 minutes Temperature – 140 oC Mg Flux - 1.0×1014 #/cm2 sec Pressure – 5.0×10-6 Torr
Ferrimagnetic (BaM)
•XRD patterns confirm all BTO are in (111) direction
Growth Method - Making use of Molecular Beam Epitaxy at Ultra-High Vacuum
Intensity (a.u.)
Effective integration of functional oxides with semiconductors will lead to next-generation devices such as multifunctional active sensors and controllers. For the BTO/MgO/Si system, through molecular beam epitaxy (MBE), the use of a magnesium oxide (MgO) template layer and the interface formation mechanisms of an oxygen bridge have been investigated for effective heteroepitaxy of high-quality ferroelectric barium titanate (BTO). Result showed that the engineered MgO surface is both effective and necessary to promote the pseudo-hexagonal heteroepitaxy of BTO(111). The relative flux relationship between Ba and Ti must be controlled, and the relationship between temperature, relative fluxes, and surface composition and structure explored discussed.
• High dielectric constant
Katherine S.
1 Ziemer
University Chemical Engineering Department, Boston. 2Massachusettes Institute of Technology, MA, USA
ABSTRACT
Functional Oxides
1 Golshan ,
?
TiO
XPS characterization of the BTO films indicates excess Ti flux produces mixed Ti 4+ and Ti 2+ bonding states.
N(E)
472
Initial BTO films grown on the MgO(111)/SiC(0001) are single crystalline with (111) orientation and show a 3D growth pattern 470
468
466
464 462 460 458 Binding Energy (eV)
456
454
452
Initial ferroelectric characterization shows surface polarity domains that MAY correspond to steps in SiC and MgO surfaces While there is measureable impact of applied voltage to film polarity, much more needs to be understood to improve potential device performance
Ti 2p
REFERENCES 40.5 Amps
41 Amps
43 Amps
45 Amps
1. R. Droopad et al, Microelectronic Engineering 109, 290–293, (2013) 2. A.R. Meier et al, Journal of Crystal Growth 294 , 401 -406, (2006) 3. V. Vaithyanathan et al, Journal of applied physics 100, 024108, (2006)
Understanding Interface Formation Interactions Between BTO/MgO/SiC By Epitaxial Growth of BaTiO3 Thin Film On SiC (0001) Negar 1Northeastern
Zhuhua
2 Cai ,
Emma
1 Kaeli ,
RESULTS
METHOD
INTRODUCTION Interface Engineering of Functional Oxide Multilayer Heterostructures to Enable Next-Generation Electronic Devices
Piezoelectric (PZT) Ferroelectric( BTO)
Wide Band Gap Semiconductor (SiC)
Cleaning Method - 6H-SiC substrates cleaned in ex-situ hydrogen furnace
20
- 330-370, C0=(A/d)*ε0
270 K Orthorhombic
300 K Tetragonal
40
45
50
55
•Surface polarization shows switching by EFM
1. Cleaned 6h-Sic (0001) Substrate - smooth, stepped surface with a √3×√3 R30 surface reconstruction
RMS: 0.43 nm
SiC (0001) √3×√3 R30°
200nm
•Impact of voltage change measureable but…
MgO(111)
SiC(0001)
MgO (111) (1x1)-OH
TiO2 Ti 2p
3. BaTiO3 Growth on MgO/SiC by MBE Finding optimum flux for Ti by holding barium flux, oxygen species, and substrate temperature (650 oC) constant - Growth Conditions: Time - 30 min Temperature - 680 oC Ba flux = 1.0×1014 #/cm2 sec Ti current - 45, 43, 41, 40.5 A Pressure - 5.0×10-6 Torr Excess titanium promotes TiO oxidation state
The engineered MgO template is both effective and necessary to promote the heteroepitaxy of BTO
Min: 765Max: 655Max: 4826 684Max: 700Max: 4155 4776 5569
400 K Cubic
• BTO, thin films consisting of poly crystalline BTO tend to stabilize cubic symmetry! Challenges: •Crystalline structure control •Stoichiometry control •Plane alignment •Effective integration with hetero substrate
good tools….
35
CONCLUSION
Tuomas H. E. et all, March 4, 2013
Molecular Beam Epitaxy and Ultra-high Vacuum
30
RESULTS
200nm
170K Rhombohedral
25
2 theta
Pink: Ti4+ Blue: Ba2+ Red: O2+
- for BTO [111] d33, f= 124 pm V-1 and BTO [001] d33, f= 35 pm V-1
BTO(111)
6H-SiC(0007) 6H-SiC(0008)
RMS: 0.45 nm
BaTiO3 (BTO): • Perovskite Ferroelectric • Strong piezoelectric effect
6H-SiC(0006)
Analysis - In-Situ: X-Ray Photoelectron Spectroscopy (Orange), Reflection High-Energy Electron Diffraction (Blue) - Ex-Situ: Field Emission SEM ,Scanning Force Microscopy (AFM, MFM, EFM)
2. MgO Growth on 6H-SiC by MBE - Growth Conditions: Time – 10 minutes Temperature – 140 oC Mg Flux - 1.0×1014 #/cm2 sec Pressure – 5.0×10-6 Torr
Ferrimagnetic (BaM)
•XRD patterns confirm all BTO are in (111) direction
Growth Method - Making use of Molecular Beam Epitaxy at Ultra-High Vacuum
Intensity (a.u.)
Effective integration of functional oxides with semiconductors will lead to next-generation devices such as multifunctional active sensors and controllers. For the BTO/MgO/Si system, through molecular beam epitaxy (MBE), the use of a magnesium oxide (MgO) template layer and the interface formation mechanisms of an oxygen bridge have been investigated for effective heteroepitaxy of high-quality ferroelectric barium titanate (BTO). Result showed that the engineered MgO surface is both effective and necessary to promote the pseudo-hexagonal heteroepitaxy of BTO(111). The relative flux relationship between Ba and Ti must be controlled, and the relationship between temperature, relative fluxes, and surface composition and structure explored discussed.
• High dielectric constant
Katherine S.
1 Ziemer
University Chemical Engineering Department, Boston. 2Massachusettes Institute of Technology, MA, USA
ABSTRACT
Functional Oxides
1 Golshan ,
?
TiO
XPS characterization of the BTO films indicates excess Ti flux produces mixed Ti 4+ and Ti 2+ bonding states.
N(E)
472
Initial BTO films grown on the MgO(111)/SiC(0001) are single crystalline with (111) orientation and show a 3D growth pattern 470
468
466
464 462 460 458 Binding Energy (eV)
456
454
452
Initial ferroelectric characterization shows surface polarity domains that MAY correspond to steps in SiC and MgO surfaces While there is measureable impact of applied voltage to film polarity, much more needs to be understood to improve potential device performance
Ti 2p
REFERENCES 40.5 Amps
41 Amps
43 Amps
45 Amps
1. R. Droopad et al, Microelectronic Engineering 109, 290–293, (2013) 2. A.R. Meier et al, Journal of Crystal Growth 294 , 401 -406, (2006) 3. V. Vaithyanathan et al, Journal of applied physics 100, 024108, (2006)
