Recent Publications

2016:

T. Hadamek, A. B. Posadas, A. Dhamdhere, D. J. Smith, and A. A. Demkov, "Spectral identification scheme for epitaxially grown single-phase niobium dioxide," J. Appl. Phys. 119, 095308 (2016).
H.-W. Wu, T. Aoki, A. B. Posadas, A. A. Demkov, and D. J. Smith, "Anti-phase boundaries at the SrTiO₃/Si (001) interface studied using aberration-corrected scanning transmission electron microscopy," Appl. Phys. Lett. 108, 091605 (2016)
C. Hu, M. D. McDaniel, A. Jiang, A. Posadas, A. A. Demkov, J. G. Ekerdt, and E. T. Yu, "A Low-Leakage Epitaxial High-k Gate Oxide for Germanium Metal-Oxide-Semiconductor Devices," AC Appl. Mater. Interfaces 8, 5416 (2016)
S. Lu, K. J. Kormondy, T. Q. Ngo, T. Aoki, A. B. Posadas, J. G. Ekerdt, A. A. Demkov, M. R. McCartney, and D. J. Smith, "Spectrum and phase mapping across the epitaxial γ-Al₂O₃/SrTiO₃ interface," Appl. Phys. Lett. 108, 051606 (2016).

2015:

M. D. McDaniel, T. Q. Ngo, S. Hu, A. Posadas, A. A. Demkov, and J. G. Ekerdt, "Atomic layer deposition of perovskite oxides and their epitaxial integration with Si, Ge, and other semiconductors," Appl. Phys. Rev. 2, 041301 (2015).
R. C. Hatch, M. Choi, A. B. Posadas, and A. A. Demkov, "Comparison of acid-and non-acid-based surface preparations of Nb-doped SrTiO₃ (001)," J. Vac. Sci. Technol. B 33, 061204 (2015).
T. Q. Ngo, N. J. Goble, A. Posadas, K. J. Kormondy, S. Lu, M. D. McDaniel, J. Jordan-Sweet, D. J. Smith, X. P. A. Gao, a. A. Demkov, and J. G. Ekerdt, "Quasi-Two-Dimensional Electron Gas at the Interface of γ-Al₂O₃/SrTiO₃ Heterostructures Grown by Atomic Layer Deposition," J. Appl. Phys. 118, 115303 (2015).
C. Lin, A. Posadas, T. Hadamek, and A. A. Demkov, "Final-state effect on x-ray photoelectron spectrum of nominally d¹ and n-doped d⁰ transition-metal oxides," Phys. Rev. B 92, 035110 (2015).
M. Choi, C. Lin, M. Butcher, C. Rodriguez, Q. He, A. Posadas, A. Y. Borisevich, S. Zollner, and A. A. Demkov, "Quantum confinement in transition metal oxide quantum wells," Appl. Phys. Lett. 106, 192902 (2015).
A. A. Demkov, P. Ponath, K. Fredrickson, A. B. Posadas, M. D. McDaniel, T. Q. Ngo, and J. G. Ekerdt, "Integrated films of transition metal oxides for information technology," Microelectron. Eng. 147, 215 (2015).
K. J. Kormondy, S. Abel, F. Fallegger, Y. Popoff, P. Ponath, A. B. Posadas, M. Sousa, D. Caimi, H. Siegwart, E. Uccelli, L. Czornomaz, C. Marchiori, J. Fompeyrine, and A. A. Demkov, "Analysis of the Pockels effect in ferroelectric barium titanate thin films on Si(001)," Microelectron. Eng. 147, 215 (2015).
T. Q. Ngo, M. D. McDaniel, A. Posadas, A. A. Demkov, and J. G. Ekerdt, "Oxygen Vacancies at the γ-Al₂O₃/STO Heterointerface Grown by Atomic Layer Deposition," Mater. Res. Soc. Symp. Proc. 1730, 294 (2015).
K. Kormondy, A. Posadas, T. Q. Ngo, S. Lu, J. L. Jordan-Sweet, X. Guo, D. J. Smith, M. R. McCartney, J. G. Ekerdt, and A. A. Demkov, "Quasi-two-dimensional electron gas at the epitaxial alumina/SrTiO₃ interface: control of oxygen vacancies," J. Appl. Phys. 117, 095303 (2015).
M. D. McDaniel, C. Hu, S. Lu, T. Ngo, A. Posadas, A. Jiang, D. J. Smith, E. T. Yu, A. A. Demkov, J. G. Ekerdt, "Atomic layer deposition of crystalline SrHfO₃ directly on Ge (001) for high-k dielectric applications," J. Appl. Phys. 117, 054101 (2015).
P. Ponath, K. Fredrickson, A. B. Posadas, Y. Ren, X. Wu, R. K. Vasudevan, M. B. Okatan, S. Jesse, T. Aoki, M. R. McCartney, D. J. Smith, S. V. Kalinin, K. Lai, and A. A. Demkov, "Carrier density modulation in a germanium heterostructure by ferroelectric switching," Nat. Comm. 6, 6067 (2015).

2014:

L. Ji, M. D. McDaniel, L. Tao, X. Li, A. B. Posadas, Y.-F. Chang, A. A. Demkov, J. G. Ekerdt, D. Akinwande, R. S. Ruoff, J. C. Lee, and E. T. Yu, "Atomic Scale Engineering of Metal-Oxide-Semiconductor Photoelectrodes for Energy Harvesting Application Integrated with Graphene and Epitaxy SrTiO₃," IEEE - Int. Electron. Devices Meet. (IEDM) 2014, 8.6.1.
A. O'Hara, T. N. Nunley, A. B. Posadas, S. Zollner, and A. A. Demkov, "Electronic and Optical Properties of NbO₂," J. Appl. Phys. 116, 213705 (2014).
L. Ji, M. D. McDaniel, S. Wang, A. B. Posadas, X. Li, H. Huang, J. C. Lee, A. A. Demkov, A. J. Bard, J. G. Ekerdt, and E. T. Yu, "A silicon-based photocathode for water reduction with an epitaxial SrTiO₃ protection layer and a nanostructured catalyst," Nat. Nanotechnol. (2014).
C. Mitra, C. Lin, A. B. Posadas, and A. A. Demkov, "Role of oxygen vacancies in room-temperature ferromagnetism in cobalt-substituted SrTiO₃,'' Phys. Rev. B 90, 125130 (2014).
C. Hu, M. D. McDaniel, A. B. Posadas, A. A. Demkov, J. G. Ekerdt, and E. T. Yu, "Highly Controllable and Stable Quantized Conductance and Resistive Switching Mechanism in Single-Crystal TiO₂ Resistive Memory on Silicon,'' Nano Lett. 14, 4360 (2014).
M. Choi, A. B. Posadas, C. A. Rodriguez, A. O'Hara, H. Seinige, A. J. Kellock, M. M. Frank, M. Tsoi, S. Zollner, V. Narayanan, and A. A. Demkov, "Structural, optical and electrical properties of strained La-doped SrTiO₃ films," J. Appl. Phys. 116, 043705 (2014).
K. J. Kormondy, A. B. Posadas, A. Slepko, A. Dhamdhere, D. J. Smith, K. N. Mitchell, T. I. Willett-Gies, S. Zollner, L. G. Marshall, J. Zhou, and A. A. Demkov, "Epitaxy of polar semiconductor Co₃O₄ (110): growth, structure, and characterization," J. Appl. Phys. 115, 243708 (2014).
K. D. Fredrickson, P. Ponath, A. B. Posadas, M. R. McCartney, T. Aoki, D. J. Smith, and A. A. Demkov, "Atomic and electronic structure of the ferroelectric BaTiO₃-Ge (001) interface," Appl. Phys. Lett 104, 242908 (2014).
M. D. McDaniel, A. Posadas, T. Q. Ngo, C. M. Karako, J. Bruley, M. M. Frank, V. Narayanan, A. A. Demkov, and J. G. Ekerdt, "Incorporation of La in epitaxial SrTiO₃ thin films grown by atomic layer deposition on SrTiO₃-buffered Si (001) substrates," J. Appl. Phys. 115, 224108 (2014).
M. D. McDaniel, T. Q. Ngo, A. Posadas, C. Hu, S. Lu, D. J. Smith, E. T. Yu, A. A. Demkov, and J. G. Ekerdt, "A Chemical Route to Monolithic Integration of Crystalline Oxides on Semiconductors,'' to appear in Advanced Materials Interfaces (2014).
H. Seo, R. C. Hatch, P. Ponath, M. Choi, A. B. Posadas, and A. A. Demkov, "Critical differences in the surface electronic structure of Ge(001) and Si(001): Ab initio theory and angle-resolved photoemission spectroscopy," Phys. Rev. B 89, 115318 (2014)
T. Q. Ngo, A. B. Posadas, M. D. McDaniel, C.Hu, J. Bruley, E. T. Yu, A. A. Demkov, and J. G. Eerdt, "Epitaxial c-axis oriented BaTiO₃-buffered Si(001) by atomic layer deposition," Appl. Phys. Lett. 104, 082910 (2014)
A. B. Posadas, A. O'Hara, S. Rangan, R. A. Bartynski, and A. A. Demkov, "Band gap of epitaxial in-plane-dimerized single-phase NbO₂ films," Appl. Phys. Lett. 104, 092901 (2014).

2013:

C. Hu, K. W. Park, A. Posadas, J. L. Jordan-Sweet, A. A. Demkov, and E. T. Yu, "Voltage-controlled ferromagnetism and magnetoresistance in LaCoO₃/SrTiO₃ heterostructures," J. Appl. Phys. 114, 183909 (2013).
A. B. Posadas, C. Lin, A. A. Demkov, and S. Zollner, "Bandgap engineering in perovskite oxides: Al-doped SrTiO₃," Appl. Phys. Lett. 103, 142906 (2013).
R. C. Hatch, K. D. Fredrickson, M. Choi, C. Lin, H. Seo, A. B. Posadas, and A. A. Demkov, "Surface electronic structure for various surface preparations of Nb-doped SrTiO3 (001)," J. Appl. Phys. 114, 103710 (2013).
C. Dubourdieu, J. Bruley, T. M. Arruda, A. Posadas, J. Jordan-Sweet, M. M. Frank, E. Cartier, D. J. Frank, S. V. Kalinin, A. A. Demkov, and V. Narayanan, "Switching of ferroelectric polarization in epitaxial BaTiO₃ films on silicon without a conducting bottom electrode," Nat. Nanotechnol. 8, 748 (2013).
T. Q. Ngo, A. Posadas, H. Seo, S. Hoang, M. D. McDaniel, D. Utess, D. H. Triyoso, C. B. Mullins, A. A. Demkov, and J. G. Ekerdt, "Atomic layer deposition of photoactive CoO/SrTiO₃ and CoO/TiO₂ on Si(001) for visible light driven photoelectrochemical water oxidation," J. Appl. Phys. 114, 084901 (2013).
A. A. Demkov, A. B. Posadas, H. Seo, M. Choi, K. J. Kormondy, P. Ponath, R. C. Hatch, M. D. McDaniel, T. Q. Ngo and J. G. Ekerdt, "Monolithic Integration of Oxides on Semiconductors," ECS Transactions 54, 255 (2013).
L. Schlipf, A. Slepko, A. B. Posadas, H. Seinige, A. Dhamdhere, M. Tsoi, D. J. Smith and A. A. Demkov, "Epitaxial Zintl aluminide SrAl₄ grown on a LaAlO3 substrate," Phys. Rev. B 88, 045314 (2013)
H. Seo, M. Choi, A. B. Posadas, R. C. Hatch and A. A. Demkov, "Combined in-situe photoemission spectroscopy and density functional theory of the Sr Zintl template for oxide heteroepitaxy on Si(001)," J. Vac. Sci. Technol. B 31, 04D107 (2013)
K. Fredrickson, A. B. Posadas, A. A. Demkov, C. Dubourdieu and J. Bruley, "Wetting at the BaTiO₃ interface," J. Appl. Phys. 113, 184102 (2013).
A. Posadas, C. Mitra, C. Lin, A. Dhamdere, D. J. Smith, M. Tsoi and A. A. Demkov, "Oxygen vacancy-mediated room-temperature ferromagnetism in insulating cobalt-substituted SrTiO₃ epitaxially integrated with silicon," Phys. Rev. B 87, 144422 (2013).
P. Ponath, A. B. Posadas, R. C. Hatch and A. A. Demkov, "Preparation of a clean Ge(001) surface using oxygen plasma cleaning, " J. Vac. Sci. Technol. B 31, 031201 (2013)
T. Q. Ngo, A. Posadas, M. D. McDaniel, D. A. Ferrer, J. Bruley, C. Breslin, A. A. Demkov, and J. G. Ekerdt, "Epitaxial growth of LaAlO₃ on SrTiO₃-buffered Si (001) substrates by atomic layer deposition," J. Cryst. Growth 363, 150 (2013)
M. Choi, A. B. Posadas, H. Seo, R. C. Hatch, and A. A. Demkov, "Charge transfer in Sr Zintl template on Si(001)," Appl. Phys. Lett. 102, 031604 (2013).
R. Dargis, A. Clark, E. Arkun, R. Roucka, R. Smith, A. A. Demkov and M. Lebby, "Growth and application of epitaxial heterostructures with polymorphous rare-earth oxides," J. Cryst. Growth 378, 177 (2013).
M. D. McDaniel, A. Posadas, T. Q. Ngo, A. Dhamdhere, D. J. Smith, A. A. Demkov, and J. G. Ekerdt, "Epitaxial strontium titanate films grown by atomic layer deposition on SrTiO₃-buffered Si(001) substrates", J. Vac. Sci. Technol. A 31, 01A136 (2013).

2012:

H. Seo, A. B. Posadas, C. Mitra, J. Ramdani, A. V. Kvit, and A. A. Demkov, "Band alignment and electronic structure of the anatase TiO₂/SrTiO₃ heterostructure integrated on Si(001)," Phys. Rev. B 86, 075301 (2012).
M.D. McDaniel, A. Posadas, T. Wang, A. A. Demkov, and J. G. Ekerdt, "Growth and characterization of epitaxial anatase TiO₂(001) on SrTiO₃-buffered Si(001) using atomic layer deposition," Thin Solid Films 520, 6525 (2012).
H. Seo, A. B. Posadas, and A.A. Demkov, "First-principles study of the growth thermodynamics of Pt on SrTiO₃ (001)", J. Vac. Sci. Technol. B 30, 04E108 (2012).
M.D. McDaniel, A. Posadas, T.Q. Ngo, A. Dhamdhere, D.J. Smith, A.A. Demkov and J.G. Ekerdt , "Growth of epitaxial oxides on silicon using atomic layer deposition: crystallization and annealing of TiO₂ on SrTiO₃-buffered Si(001)", J. Vac. Sci. Technol. B 30, 04E111 (2012).
M. Choi, A. Posadas, R. Dargis, C-K Shih, A.A. Demkov, D.H. Triyoso, N.D. Theodore, C. Dubourdieu, J. Bruley, and J. Jordan-Sweet, "Strain relaxation in single crystal SrTiO₃ grown on Si (001) by molecular beam epitaxy," J. Appl. Phys. 111, 064112 (2012)
R. Dargis, E. Arkun, A. Clark, R. Roucka, R. Smith, D. Williams, M. Lebby, and A.A. Demkov, “Rare-earth-metal oxide buffer for epitaxial growth of single crystal GeSi and Ge on Si(111)”, J. of Vac. Sci. Technol. B 30, (2012).

2011:

A.A. Demkov, A. Posadas, H. Seo and J.K. Lee, “Physics of oxides heterostructures’, ECS Trans. 41, 275 (2011).
A.A. Demkov, A. Posadas, H. Seo, J.K. Lee and N. Sai, “Emerging physics of oxide heterostructures”, phys. stat. sol. b, 248, 2076 (2011).
A. Posadas, M. Berg, H. Seo, D.J. Smith, H. Celio, A.P. Kirk, D. Zhernokletov, R.M. Wallace, A. de Lozanne, and A.A. Demkov, “Strain-induced ferromagnetism in LaCoO₃: Theory and growth on Si (100)”, Microel. Eng. 88, 1444 (2011).
A. Posadas, R. Dargis, M. Choi, A. Slepko, J.J. Kim, D.J. Smith, and A.A. Demkov, “Formation of single-orientation epitaxial islands of TiSi₂ on Si (001) using Sr passivation”, J. Vac. Sci. Technol. B 23, 1071 (2011)..
A. Posadas, M. Berg, H. Seo, D.J. Smith, H. Celio, A.P. Kirk, D. Zhernokletov, R.M. Wallace, A. de Lozanne, and A.A. Demkov, “Strain-induced ferromagnetism in correlated oxide LaCoO₃ epitaxially grown on Si (100)”, Appl. Phys. Lett. 98, 055104 (2011).