Epitaxial c-axis oriented BaTiO3 thin films on SrTiO3-buffered Si(001) by atomic layer deposition

Atomic layer deposition (ALD) of epitaxial c-axis oriented BaTiO3 (BTO) on Si(001) using a thin (1.6 nm) buffer layer of SrTiO3 (STO) grown by molecular beam epitaxy is reported. The ALD growth of crystalline BTO films at 225  °C used barium bis(triisopropylcyclopentadienyl), titanium tetraisopropoxide, and water as co-reactants. X-ray diffraction (XRD) reveals a high degree of crystallinity and c-axis orientation of as-deposited BTO films. Crystallinity is improved after vacuum annealing at 600  °C. Two-dimensional XRD confirms the tetragonal structure and orientation of 7–20-nm thick films. The effect of the annealing process on the BTO structure is discussed. A clean STO/Si interface is found using in-situ X-ray photoelectron spectroscopy and confirmed by cross-sectional scanning transmission electron microscopy. The capacitance-voltage characteristics of 7–20 nm-thick BTO films are examined and show an effective dielectric constant of ∼660 for the heterostructure.

[1]  M D Rossell,et al.  Controlling tetragonality and crystalline orientation in BaTiO3 nano-layers grown on Si , 2013, Nanotechnology.

[2]  J. Woicik,et al.  c-axis oriented epitaxial BaTiO3 films on (001) Si , 2006 .

[3]  A. Demkov,et al.  Band alignment and electronic structure of the anatase TiO2/SrTiO3(001) heterostructure integrated on Si(001) , 2012 .

[4]  Catherine Dubourdieu,et al.  Strain Relaxation in Single Crystal SrTiO3 Grown on Si (001) by Molecular Beam Epitaxy , 2012 .

[5]  A. Ganguli,et al.  Polymeric citrate precursor route to the synthesis of nano-sized barium lead titanates , 2003 .

[6]  Hao Li,et al.  Two-dimensional growth of high-quality strontium titanate thin films on Si , 2003 .

[7]  Ravi Droopad,et al.  Epitaxial oxide thin films on Si(001) , 2000 .

[8]  K. Garrity,et al.  Crystalline Oxides on Silicon , 2010, Advanced materials.

[9]  W. J. Merz,et al.  Domain Formation and Domain Wall Motions in Ferroelectric BaTiO 3 Single Crystals , 1954 .

[10]  R. Mckee,et al.  Crystalline Oxides on Silicon: The First Five Monolayers , 1998 .

[11]  J. Curless,et al.  Epitaxial perovskite thin films grown on silicon by molecular beam epitaxy , 2000 .

[12]  T. Ma,et al.  Electrical properties and interfacial structure of epitaxial LaAlO3 on Si (001) , 2009 .

[13]  Xiaolong Li,et al.  Characteristics of the low electron density surface layer on BaTiO3 thin films , 2008 .

[14]  C. Merckling,et al.  Molecular beam epitaxial growth of BaTiO3 single crystal on Ge-on-Si(001) substrates , 2011 .

[15]  Alexei Chelnokov,et al.  A strong electro-optically active lead-free ferroelectric integrated on silicon , 2013, Nature Communications.

[16]  Catherine Dubourdieu,et al.  Switching of ferroelectric polarization in epitaxial BaTiO₃ films on silicon without a conducting bottom electrode. , 2013, Nature nanotechnology.

[17]  Alexander A. Demkov,et al.  Epitaxial strontium titanate films grown by atomic layer deposition on SrTiO3-buffered Si(001) substrates , 2013 .

[18]  Xiaoqing Pan,et al.  Experimental evidence of ferroelectric negative capacitance in nanoscale heterostructures , 2011, 1103.4419.

[19]  Wim Bogaerts,et al.  Preferentially oriented BaTiO3 thin films deposited on silicon with thin intermediate buffer layers , 2013, Nanoscale Research Letters.

[20]  Bruce W Wessels,et al.  Epitaxial growth and strain relaxation of BaTiO3 thin films on SrTiO3 buffered (001) Si by molecular beam epitaxy , 2007 .

[21]  David J. Smith,et al.  Epitaxial integration of ferromagnetic correlated oxide LaCoO3 with Si (100) , 2011 .

[22]  G. Saint-Girons,et al.  Epitaxy of BaTiO3 thin film on Si(001) using a SrTiO3 buffer layer for non-volatile memory application , 2011 .

[23]  Coercive fields in ultrathin BaTiO3 capacitors , 2006, cond-mat/0609064.

[24]  S. Datta,et al.  Use of negative capacitance to provide voltage amplification for low power nanoscale devices. , 2008, Nano letters.

[25]  A. Demkov,et al.  Growth and characterization of epitaxial anatase TiO2(001) on SrTiO3-buffered Si(001) using atomic layer deposition , 2012 .

[26]  R. Mckee,et al.  Physical structure and inversion charge at a semiconductor interface with a crystalline oxide. , 2001, Science.