Publications

  1. Jiechao Jiang, Nonso Martin Chetuya, Efstathios I. Meletis, Joseph H Ngai,  Gordon J. Grzybowski and Bruce Claflin, “Temperature-dependent morphology and composition of ultra-thin GeSn epilayers prepared by remote plasma enhanced chemical vapor deposition,” submitted (2023).
  2. Jiechao Jiang, Nonso Martin Chetuya, Efstathios I. Meletis, Joseph Ngai, Bruce Claflin, and Gordon Grzybowski, “Epitaxial twin coupled microstructure in GeSn films prepared by remote plasma enhanced chemical vapor deposition,” submitted (2023).
  3. R. Sameer Annam, S. Danayat, A. Nayal, F. Tarannum, M. Chrysler, J. H.  Ngai, J.-C. Jiang, A. J. Schmidt, J. Garg, “Thickness Dependent Thermal Conductivity of Strontium Titanate (SrTiO3) Thin Films on Silicon (Si) Substrate,” J. Vac. Sci. Technol. A 42, 022707 (2024).
  4. “Probing the electronic properties of gap states near the surface of n-SrTiO3 / i-Si(001) heterojunctions with high sensitivity,” S. A. Chambers, Z. H. Lim, J. H. Ngai, D. Biswas, T.-L. Lee, Phys. Rev. Mater. 8, 014602 (2024).
  5. “Surface termination control of charge transfer and band alignment across a semiconductor-crystalline oxide heterojunction,” M. Chrysler, J. Gabel, T.-L. Lee, Z. Zhu, T. C. Kaspar, M. Bowden, P. V. Sushko, S. A. Chambers, and J. H. Ngai, Phys. Rev. Mater. 7, 084604 (2023).
  6. “Deposition-Last Lithographically Defined Complex Oxide Devices on Si(100)” M. Chrysler, J. C. Jiang, G. Lorkowski, E. I. Meletis, and J. H. Ngai, J. Vac. Sci. Technol. A 40, 052701 (2022).
  7. “Preface for the special topic collection honoring Dr. Scott Chambers’ 70th birthday and his leadership in the science and technology of oxide thin films,” T. C. Kaspar, Y. Du, M. H. Engelhard, D. R. Baer, B. Jalan, J. H. Ngai, J. Vac. Sci. Technol. A 40, 041602 (2022).
  8. “Effect of Buffer Termination on Intermixing and Conductivity in LaTiO3/SrTiO3 Heterostructures Integrated on Si(100)”
    T.-J. Chen, K. Ahmadi-Majlan, Z. H. Lim, Z. Zhang, J. H. Ngai, and D. P. Kumah,  J. Vac. Sci. & Technol. A 40, 013206 (2022).
  9. “Mapping hidden space-charge distributions across crystalline metal oxide/group IV semiconductor interfaces”
    S. A. Chambers, M. Chrysler, J. H. Ngai, T.-L. Lee, J. Gabel, B. E. Matthews, S. R. Spurgeon, M. E. Bowden, Z. Zhu, P. V. Sushko,  Phys. Rev. Mater. 6, 015002 (2022).
  10. “Tuning band alignment at a semiconductor-crystalline oxide heterojunction via electrostatic modulation of the interfacial dipole”
    M. Chrysler, J. Gabel, T.-L. Lee, A. N. Penn, B. E. Matthews, D. M. Kepaptsoglou, Q. M. Ramasse, J. R. Paudel, R. K. Sah, J. D. Grassi, Z. Zhu, A. X. Gray, J. M. LeBeau, S. R. Spurgeon, S. A. Chambers, P. V. Sushko, and J. H. Ngai, Phys. Rev. Mater. 5, 104603 (2021).
  11. “Suspended single-crystalline oxide structures on silicon through wet-etch techniques: effects of oxygen vacancies and dislocations on etch rates”
    Z. H. Lim, M. Chrysler, A. Kumar, J. P. Mauthe, D. P. Kumah, C. Richardson, J. M. LeBeau and J. H. Ngai,  Journal of Vacuum Science & Technology A 38, 013406 (2020).
  12. “Epitaxial oxides on semiconductors: from Fundamentals to New Devices”
    D. P. Kumah, J. H. Ngai and L. Kornblum,  Adv. Func. Mater. 1901597 (2019).
  13. “Charge transfer and tunable built-in electric fields across semiconductor-crystalline oxide interfaces”
    Z. H. Lim, N. F. Quackenbush, A. Penn, M. Chrysler, M. Bowden, Z. Zhu, J. M. Ablett, T. -L. Lee, J. M. LeBeau, J. C. Woicik, S. A. Chambers and J. H. Ngai,  Physical Review Letters 123, 026805 (2019)
  14. “Interfacial Structure of SrZrxTi1-xO3 films on Ge”
    T. J. Chen, K. Ahmadi-Majlan, Z. H. Lim, Z. Zhang, J. H. Ngai, A. F. Kemper, D. P. Kumah, Appl. Phys. Lett. 113, 201601 (2018).
  15. “Tuning metal-insulator behavior in LaTiO3/SrTiO3 heterostructures integrated directly on Si(100) through control of atomic layer thickness”
    K. Ahmadi-Majlan, T. J. Chen, Z. H. Lim, P. Conlin, R. Hensley, M. Chrysler, D. Su, H. Chen, D. P. Kumah and J. H. Ngai,  Appl. Phys. Lett. 112, 193104 (2018).
  16. “An Ultrathin Single Crystalline Relaxor Ferroelectric Integrated on a High Mobility Semiconductor”
    R. M. Moghadam, Z. Xiao, K. Ahmadi-Majlan, E. D Grimley, M. Bowden, P.-V. Ong, S. A. Chamber, J. M. Lebeau, X. Hong, P. Sushko and J. H. Ngai,  Nano Lett., 17, 6248 (2017).
  17. “Structural and electrical properties of single crystalline SrZrO3 epitaxially grown on Ge(001)”
    Z. H. Lim, K. Ahmadi-Majlan, E. D. Grimley, Y. Du, M. Bowden, R. Moghadam, J. M. Lebeau, S. A. Chambers, and J. H. Ngai,  J. Appl. Phys., 122, 084102 (2017).
  18. “Superconducting epitaxial YBa2Cu3O7-d on SrTiO3 buffered Si (001)”
    K. Ahmadi-Majlan, H. Zhang, X. Shen, M. Jahangir-Moghadam, M. Chrysler, P. Conlin, R. Hensley, D. Su, J. Y. T. Wei, and J. H. Ngai,  Bull. Mater. Sci., 41:23 (2018).
  19. “Electrically coupling complex oxides to semiconductors: a route to novel material functionalities”
    J. H. Ngai, K. Ahmadi-Majlan, J. Moghadam, M. Chrysler, D. Kumah, F. J. Walker, C. H. Ahn, T. Droubay, Y. Du, S. A. Chambers, M. Bowden, X. Shen, D. Su, Journal of Materials Research 32, 249-259 (2017) (Invited Feature Paper).
  20. “Engineered Unique Elastic Modes at a BaTiO3 / 2 × 1 – Ge 001 Interface”
    D. P. Kumah, M. Dogan, J. H. Ngai, D. Qiu, Z. Zhang, D. Su, E. D. Specht, S. Ismail-Beigi, C. H. Ahn, and F. J. Walker, Phys. Rev. Lett. 116, 106101 (2016).
  21. “Electrically Coupling Multifunctional Oxides to Semiconductors: A Route to Novel Material Functionalities”
    J. H. Ngai, K. Ahmadi-Majlan, J. Moghadam, M. Chrysler, D. P. Kumah, C. H. Ahn, F. J. Walker, T. Droubay, M. Bowden, S. A. Chambers, X. Shen, D. Su,  MRS Advances 1, 255-263 (2016).
  22. “Band-gap engineering at a semiconductor – crystalline oxide interface”
    M. Jahangir-Moghadam, K. Ahmadi-Majlan, X. Shen, T. Droubay, M. Bowden, M. Chrysler, D. Su, S. A. Chambers and J. H. Ngai,  Adv. Mat. Inter. 2, 1400497 (2015) (COVER ARTICLE).
  23. “Interfacial Structure in Epitaxial Perovskite Oxides on (001) Ge Crystal”
    X. Shen, K. Ahmadi-Majlan, J. H. Ngai, D. Wu , and D. Su,  Appl. Phys. Lett. 106,  032903 (2015).
  24. “A high density 2D electron gas in an oxide heterostructure on Si (001)”
    E. N. Jin, L. Kornblum, D. Kumah, K. Zou, C. Broadbridge, J. H. Ngai, C. H. Ahn, and F. J. Walker,  APL Mat. 2, 116109 (2014).
  25. “A silicon integrated BaTiO3 electro-optic modulator”
    C. Xiong, W. H. P. Pernice, J. H. Ngai, J. W. Reiner, D. P. Kumah, F. J. Walker, C. H. Ahn, H. Tang,  Lasers and Electro-Optics (CLEO), pp. 1-2 (2014).
  26. “Correlated Oxide Physics and Electronics”
    J. H. Ngai, F. J. Walker and C. H. Ahn,  Annu. Rev. Mater. Res. 44, 1-17 (2014)
  27. “Hysteretic electrical transport in BaTiO3/Ba(1-x)Sr(x)TiO3/Ge heterostructures”
    J. H. Ngai, D.P. Kumah, C.H. Ahn, F. J. Walker,  Appl. Phys. Lett. 104, 062905 (2014).
  28. “Active integrated optics on silicon: ferroelectric BaTiO3 devices”
    Chi Xiong, Wolfram H. P. Pernice, J. H. Ngai, James W. Reiner, Divine Kumah, Frederick J. Walker, Charles H. Ahn and Hong X. Tang,  Nano Lett., 14 (3), 1419 (2014).
  29. “Tuning the Structure of Nickelates to Achieve Two-Dimensional Electron Conduction”
    D.P. Kumah, A.S. Disa, J. H. Ngai, H. Chen, A. Malashevich, J. W. Reiner, S. Ismail-Beigi, F.J. Walker and C.H. Ahn,  Adv. Mat. 26, 1935 (2014).
  30. “Phase diagram of compressively strained nickelate thin films”
    A. S. Disa, D. P. Kumah, J. H. Ngai, E. D. Specht, D. A. Arena, F. J. Walker, and C. H. Ahn,  APL Materials 1, 032110 (2013)
  31. “Scanning SQUID susceptometry of a paramagnetic superconductor”
    J.R. Kirtley, B. Kalisky, J.A. Bert, C. Bell, M. Kim, Y. Hikita, H.Y. Hwang, J. H. Ngai, Y. Segal, F. J. Walker, C.H. Ahn, and K.A. Moler,  Physical Review B 85, 224518 (2012).
  32. “Electrostatic modulation of anisotropic magnetotransport in Ar+-irradiated SrTiO3 : Effects of boundary scattering”
    J. H. Ngai, Y. Segal, F.J. Walker, C.H. Ahn,  Physical Review B 83, 045304 (2011).
  33. “Electric field tuned crossover from classical to weakly localized quantum transport in electron doped SrTiO3”
    J. H. Ngai, Y. Segal, D. Su, Y. Zhu, F.J. Walker, S. Ismail-Beigi, K. Le Hur, C.H. Ahn,  Physical Review B Rapid Communications 81, 241307 (2010).
  34. “Local tunneling probe of (110) Y0.95Ca0.05Ba2Cu3O7-d thin films in a magnetic field”
    J. H. Ngai, R. Beck, G. Leibovitch, G. Deutscher, J.Y.T. Wei,  Physical Review B 82, 054505 (2010).
  35. “Achieving A-site Termination on La0.18Sr0.82Al0.59Ta0.41O3 substrates” 
    J. H. Ngai, T.C. Schwendemann, A.E. Walker, F.J. Walker, E.I. Altman, C.H. Ahn, Advanced Materials 22, 2945 (2010).
  36. “X-ray photoemission studies of the metal-insulator transition in LaAlO3/SrTiO3 structures grown by molecular beam epitaxy” 
    Y. Segal, J. H. Ngai, J.W. Reiner, F.J. Walker, C.H. Ahn, Physical Review B Rapid Communications 80, 241107 (2009).
  37. “Tunneling Spectroscopy on c-Axis Y1-xCaxBa2Cu3O7-d Thin Films”
    J. H. Ngai, W.A. Atkinson, J.Y.T. Wei,  Physical Review Letters 98, 177003 (2007).
  38. “Suppression of low-energy Andreev states by a supercurrent in YBa2Cu3O7-d”
    J. H. Ngai, P. Morales, J.Y.T. Wei,  Physical Review B 72, 054513 (2005).
  39. “Scanning tunneling spectroscopy under pulsed spin-injection” 
    J. H. Ngai, Y.C. Tseng, P. Morales, V. Pribiag, J.Y.T. Wei, F Chen, D.D. Perovic, Applied Physics Letters 84, 1907 (2004).
  40. “Nanoscale studies of cuprate superconductors in the current-carrying state,”
    J.Y.T. Wei, J. H. Ngai, P. Morales,  Proceedings of SPIE 5932, 593210 (2005).
  41. “Nanoscale dephasing of the high-Tc order parameter under a pair current,”
    J.Y.T. Wei, J. H. Ngai, F. Chen, P. Morales, D.D. Perovic,  Physica C 408-410, 794 (2004).