Spintronic III-V Semiconductors
Integrated Devices for Terabit Per Second 1.3 and 1.5 Micron
Network Applications
The deposition of undoped and rare-earth doped ferroelectric oxide thin films for waveguides is under development. Specific systems under investigation include thin film BaTiO3, KNbO3 and KNbTaO3. Films are prepared by metalorganic chemical vapor deposition. Low-loss thin film waveguides are being developed. The loss mechanisms are being investigated and related to thin film microstructure. The electro-optic properties of the films are determined by second harmonic generation and measurement of the electro-optic coefficient in the waveguide modulator structures. To determine the optical activity of the rare-earth impurities in the thin films, photoluminescence spectroscopy, photoluminescence decay measurements and transient photocapacitance spectroscopy are used. Structure and composition are characterized using high resolution transmission electron microscopy, analytical electron microscopy and x-ray diffraction. Correlations between optical, dielectric and structural properties with deposition parameters will be developed. Rib waveguide structures are fabricated. The suitability of these materials for electro-optic modulators, optical amplifiers and thin film solid state lasers are under study. Issues of integrating ferroelectric thin films with silicon will be elucidated.
Recent Publications on Oxide Thin
Films and Devices by Bruce W. Wessels
Sponsorship: NSF DMR-0520513, NSF ECS-0123469, DMR-0605292,
"Low loss electro-optic BaTiO3 thin film waveguide modulator," with P. Tang, D. J. Towner, A. L. Meier, and B. W. Wessels, Photonics Technology Letters, 16 8 (2004).
"Three dimensional domain structure in epitaxial barium titanate thin films," with D. J. Towner, T. J. Lansford, and B. W. Wessels, J. of Electroceramics, 13 89-93 (2004)
"Integration of MgO on Si(001) using SrO and SrTiO3 buffer layers by Molecular Beam Epitaxy," with A. Meier, F. Niu, and B. W. Wessels, Journal of Electroceramics, 13 (2004).
"Thin Film Ferroelectrics for Guided Wave Devices," by B. W. Wessels, J. of Electroceramics, 13 135-138 (2004).
"Low voltage, polarization insensitive electro-optic modulator based on polydomain barium titanate thin film," with P. Tang, D. J. Towner, A. L. Meier, and B. W. Wessels, Appl. Phys. Lett., 85 20, 4615-4617 (2004).
"Electrooptic modulation up to 40 GHz in a barium titanate thin film waveguide modulator," with P. Tang, D. J. Towner, T. Hamano, A. L. Meier, and B. W. Wessels, Optics Express, 12 24, 5962-5967 (2004).
"BaTiO3 thin film waveguide modulator with low voltage length product at near-infrared wavelengths of 0.98μm and 1.55 μm," with P. Tang, A. L. Meier, D. J. Towner, and B. W. Wessels, Optics Lett., 30 3, 254-256 (2005).
"BaTiO3 waveguide modulators with 360 pm/V effective electro-optic coefficient at 1.55 μm," with P. Tang, A. L. Meier, D. J. Towner, T. Hamano, and B. W. Wessels, Proc. Integrated Photonics Research Conference, 2004.
"Low temperature deposition of epitaxial BaTiO3 films in a rotating disk vertical MOCVD reactor," with A. M. Dhote, A. L. Meier, D. J. Towner, B. W. Wessels, J. Ni, and T. J. Marks, JVST B, 23 4, 1674-1678 (2005).
"Performance simulation for ferroelectric thin-film based waveguide electro-optic Modulators," with D.-G. Sun, Z. Liu, Y. Huang, S.-T. Ho, D. Towner, and B. W. Wessels, Optics Communications, 225, 319-330 (2005).
"High-Speed Traveling Wave BaTiO3 Thin Film Electrooptic Modulators," with P. Tang, A. L. Meier, D. J. Towner, and B. W. Wessels, Electronics Letters, 41 23, 1296-1297 (2005).
"Barium Titanate Thin Film Electro-Optic Modulator with Low Half-Wave Voltage at 1310nm," with Z. Liu, B. Liu, G. Xu, S.-T. Ho, P. Tang, A. L. Meier, D. J. Towner, and B. W. Wessels, Conference on Lasers and Electro-Optics, 3, 1870-1872 (2005)
"Ultra-wide bandwidth, thin film electro-optic modulators," with P. Tang, A. L. Meier, D. J. Towner, and B. W. Wessels, PacRim Conference Proceedings, 2005.
"Integration of BaTiO3 on Si (001) using MgO/STO buffer layers by molecular beam epitaxy," with F. Niu, A. R. Meier, and B. Wessels, J. Cryst. Growth 294, 401-406 (2006).
"Epitaxial growth and strain relaxation of MgO thin films on Si grown by molecular beam epitaxy," with F. Niu, A. L. Meier, and B. W. Wessels, J. Vac. Sci. Technol. B 24(6), 1071-1023 (2006).
"Ultra-wide bandwidth, thin film electro-optic modulators," with P. Tang, A. L. Meier, D. J. Towner, and B. W. Wessels, submitted to PacRim Conference Proceedings, 2005.
"Phase stability of hetero epitaxial polydomain BaTiO3 thin films," with A. L. Meier, A. Y. Desai, L. Wang, T. J. Marks, and B. W. Wessels, J. Mat. Research (2006).
“Complex electrical (impedance/dielectric) properties of electroceramic thin films by impedance spectroscopy with interdigital electrodes” N. J. Kidner, A. Meier,, Z. J. Homrighaus, B. W. Wessels, T. O. Mason and E. J. Garboczi, Thin Solid Films 515 4588 (2007).
“Surface and interfacial structure of epitaxial SrTiO3 thin films on (001) Si grown by molecular beam epitaxy,” with F. Niu and B.W. Wessels, J. of Crystal Growth 300 509-518, (2007).
“Phase stability of heteroepitaxial polydomain BaTiO3 thin films,” with A.L. Meier, A.Y. Desai, L. Wang, T.J. Marks and B.W. Wessels, J. Mater. Res., 22, 1354 (2007).
“Nonlinear photonic crystal waveguide structures based on barium titanate thin films and their optical properties,” with Z.F. Liu, P.T. Lin, B.W. Wessels et al., Appl. Phys. Lett. 90 201104, (2007).
“Investigation of heteroepitaxial growth of magnetite thin films,” with G.E. Sterbinsky, J. Cheng, P.T. Chiu, B.W. Wessels, and D.J. Keavney, J. Vac. Sci. Technol. B 25, 1359 (2007).
“Epitaxial Fe3O4 on SrTiO3 characterized by transmission electron microscopy,” with J.G. Zheng, G.E. Sterbinsky, J. Cheng, and B.W. Wessels, , J. Vac. Sci. Technol. B 25, 659 (2007).
“Ferroelectric epitaxial thin films for integrated optics” B. W. Wessels, Ann. Rev. Mater. Res. 37 659 (2007)
“Bragg reflector waveguide and electro-optic modulator based on barium titanate epitaxial thin films,” with Z. Liu, P.T. Lin, and B.W. Wessels, MRS Proc., 1014 (2007).
“Simulation and fabrication of two dimensional nonlinear photonic crystals using barium titanate thin films,” with P.T. Lin, Z. Liu, and B.W. Wessels, MRS Proc. 1014 (2007).
"Cascaded Bragg reflectors for a barium titanate thin film electro-optic modulator," with Z. Liu, P.-T. Lin, and B. W. Wessels, J. of Optics A, 10, 015302 (2008).
“Highly efficient broadband second harmonic generation using polydomain epitaxial barium titanate thin film waveguides,” with Pao Tai Lin and Bruce W. Wessels, Appl. Phys. Lett., 92 221103 ( 2008).
“Magnetic and magneto-optical properties of heteroepitaxial magnetite thin films,” with J. Cheng, G.E. Sternbinsky, B.W. Wessels, Journal of Crystal Growth, 310 16, 3730-3734 (2008).
“Dynamic response of polydomain ferroelectric barium titanate epitaxial thin films and its field dependence,” with Zhifu Liu, A.L. Meier, and B. W. Wessels, Journal of Appl. Phys., 104 064115 (2008).
“Interfacial structure and chemistry of CoFe2O4 thin films on SrTiO3 and MgO substrates,” with J.Cheng, V.P. Dravid, S. Xie and B.W. Wessels, Appl. Phys. Lett., 93, 181901 (2008).
Recent Publications on III-V Semiconductors by Bruce W. Wessels
(supported by NASA NAG5-11457)
"Phonon Assisted Deep Level Luminescence in Heavily Mg Doped InGaN," with B. Han, M. P. Ulmer, and B. W. Wessels, J. Electronic Mat, 33, 5, 431-435 (2004).
"Deep donor-acceptor pair luminescence in co-doped GaN," B. Han, J. M. Gregie, M. P. Ulmer and B. W. Wessels, MRS Proceedings 743 L5.8.1-L5.8.6 (2004).
"Investigation of composition fluctuations in GaN:Mg using optical transmission spectroscopy, near-field scanning optical microscopy and scanning Kelvin probe microscopy," with B. Han, B. W. Wessels, and M. P. Ulmer, J. Appl. Phys, 97 1, 023513: 1-6, (2005).
"Three-dimensional nanoscale composition mapping of semiconductor nanowires," with D. E. Perea, J. E. Allen, S. J. May, B. W. Wessels, D. N. Seidman, and L. J. Lauhon, Nano Letters, 6 2, 181-185 (2006).
"Investigation of nanoscale composition fluctuations in InGaN using optical transmission spectroscopy and near-field scanning optical microscopy," with B. Han, B. Wessels, and M. Ulmer, Journal of Applied Physics 99, 084312 (2006).
Recent Publications on Spintronic III-V Semiconductors by Bruce W. Wessels
(supported by NSF ECS-0224210, NSF DMR-0076077)
"Local Structure Around Mn Atoms in Room-Temperature Ferromagnetic (In,Mn)As Thin Films Probed by Extended X-ray Absorption Fine Structure," with Y. L. Soo, S. Kim, Y. H. Kao, A. J. Blattner, B. W. Wessels, S. Khalid, C. Sanchez Hanke, and C.-C. Kao, Appl. Phys. Lett. 84, 2004.
"Optical properties of Mn doped InAs and InMnAs epitaxial films," with P. T. Chiu, A. J. Blattner, S. J. May, and B. W. Wessels, Physica B, 344 379-384 (2004).
"Room-temperature magneto-optical activity of InMnAs thin films," with P. T. Chiu, S. J. May, and B. W. Wessels, Appl. Phys. Lett., 85 5 (2004).
"Optical properties of Mn4+ ions in GaN:Mn codoped with Mg acceptors," with B. Han, R. Y. Korotkov, and B. W. Wessels, Appl. Phys. Lett., 84 26 (2004).
"Negative magnetoresistance in (In,Mn)As semiconductors," with S. J. May, A. J. Blattner, and B. W. Wessels, Physical Review B, 70 073303 (2004).
"Magnetic anisotropy in epitaxial InMnAs," with P. T. Chiu, S. J. May, A. J. Blattner, and B. W. Wessels, Proc. ICPS, 2004.
"Local Environment of Ferromagnetically Ordered Mn in Epitaxial InMnAs," with P. T. Chiu, B. W. Wessels, D. J. Keavney, and J. W. Freeland, Appl. Phys. Lett., 86 072505, 1-3 (2005).
"Optical investigation of electronic states of Mn4+ ions in p-type GaN," with B. Han and B. W. Wessels, Appl. Phys. Lett., 86 042505, 1-3 (2005).
"Dendritic nanowire growth by a self-assemble catalyst" with S. J. May, J-G. Zheng, B. W. Wessels and L. J. Lauhon, Advanced Materials, 17 598-602 (2005).
"Electronic and magnetotransport properties of ferromagnetic p-(In,Mn)As/n-InAs heterojunctions", with S. J. May and B. W. Wessels, JVST B, 23 4, 1769-1772 (2005).
"Magnetic anisotropy in epitaxial InMnAs," with P. T. Chiu, S. J. May, A. J. Blattner, and B. W. Wessels, Physics of Semiconductors, AIP Conference Proceedings, 772 347 (2005).
"Ferromagnetic Self-Assembled Quantum Dots on Semiconductor Nanowires," with D. G. Ramlan, S. J. May, J.-G. Zheng, J. E. Allen, B. W. Wessels, and L. J. Lauhon, Nano Letters, 6 1, 50-54 (2006).
"Direct observation of room temperature magnetism in (In,Mn)As thin films by magnetic force microscopy," with S. J. May, A. J. Blattner, D. P. Eam, and B. W. Wessels, Applied Surface Science, 252 10, 3509-3513 (2005).
"High field magnetoresistance in p-(In,Mn)An/n-InAs heterojunctions," with S. J. May and B. W. Wessels, Applied Physics Letters, 88 7, 072105 (2005).
"Origin of uniaxial magnetic anisotropy in epitaxial InMnAs this films," with P. Chiu, S. May, and B. Wessels, Journal of Applied Physics 99, 083907 (2006).
"Evidence of room temperature sp-d exchange in InMnAs epitaxial films," with P. T. Chiu and B. Wessels, Applied Physics Letters 89, 102505 (2006).
"Magnetic properties of MnAs thin films on GaAs(001) by MOVPE," with G. E. Sterbinsky, S. J. May, P. T. Chiu, and B. Wessels, Physica C (2006).
"Composition analysis of single semiconductor nanowires using pulsed-laser atom probe tomography," with D. E. Perea, J. L. Lensch, S. J. May, B. W. Wessels, and L. J. Lauhon, Applied Physics A 85, 271-275 (2006).
"Negative magnetoresistance in Ni/oxide/InMnAs tunnel junctions," with S. J. May and B. Wessels, Journal of Applied Physics 100, 053912 (2006).
“Dependence of magnetic circular dichroism on doping and temperature dependence in In1-xMnxAs epitaxial films” P. T. Chiu and B. W. Wessels, Phys. Rev. B 76 165201 (2007).
“Ferromagnetic semiconductors and the role of disorder,” by Bruce W. Wessels, New Journal of Physics, 10, 055008 ( 2008).
“Magnetocapacitance effect in InMnAs/InAs p-n heterojunctions,” with N. Rangaraju and B.W. Wessels, Journal of Vacuum Science & Technology B, 26 4, 1526-1529 (2008).
“Structural and Magnetic Properties of Ferromagnetic In1-xMnxAs1-yPy layers,” with N. D. Parashar, P. T. Chiu, and B. W. Wessels, Journal of Magnetism and Magnetic Materials (2009).
“Reflectance Magnetic Circular Dichroism Studies at the point in InMnAs Semiconductor Films” with N.D. Parashar, P.T. Chiu, and Bruce Wessels, Physica E (2009). In press
“InMnAs Thin Films and Heterostructures,” by Bruce W. Wessels, in Semiconductor Spintronics (World Scientific 2009). In press