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 by Bruce W. Wessels
Sponsorship: NSF DMR-0520513, NSF ECS-0123469, DMR-0605292
"Epitaxial Ferroelectric BaTiO3 Thin Films for Microphotonic Applications," with F. Niu, A.R. Teren, B.H. Hoerman, and B.W. Wessels. MRS Proceedings, 637 (2001).
"Thin Film BaTiO3 Electrooptic Modulator and Its Dynamic Response," with S.-S. Kim, D. Towner, A. Teren, B. W. Wessels, S.-S. Chang, and S.-T. Ho. Proceedings of the Integrated Photonics Research Conference, (OSA, 2001).
"Erbium-Doped Barium Titanate Thin Film Waveguides for Integrated Optical Amplifiers", with A. R. Teren, S.-S. Kim, S.-T. Ho, and B. E. Wessels, Mat. Res. Soc. Symp. Proc., 688 K9.7.1-6 (2002).
"Dielectric Properties of Epitaxial KNbO3 Ferroelectric Thin Films," with S. Chattopadhyay, B. M. Nichols, J.H. Hwang, T.O. Mason, and B.W. Wessels. J.Mat. Research 17 (2002).
"Diffuse Phase Transition in Epitaxial BaTiO3 Thin Films," with S. Chattopadhyay, A.R. Teren, J.H. Hwang, T.O. Mason, and B.W. Wessels. J.Mat. Research 17 669 (2002).
"Fast time resolved x-ray diffraction in BaTiO3 films subjected to a strong high-frequency electric field," E. Zolotoyabko, J. P. Quintana, B. H. Hoerman and B. W. Wessels. Appl. Phys. Lett 80, 3159 (2002).
"Dynamic Response of the Dielectric and Electro-optic Properties of Epitaxial Ferroelectric Thin Films," with B. H. Hoerman, B. M. Nichols, and B. W. Wessels. Physical Review B 65 224110 (2002).
"Phase stability of epitaxial KTaxNb1-xO3 thin films deposited by metalorganic chemical vapor deposition," B. M. Nichols, B. H. Hoerman, J. H. Hwang, et al. J. Mater. Res. 18 (1) 106 (2003).
"Effects of two-stage deposition on the structure and properties of heteroepitaxial BaTiO3 thin films," D. J. Towner, J. Ni, T. J. Marks and B. W. Wessels, J. of Crystal Growth 255 107-113 (2003).
"Nanosecond-scale domain dynamics in BaTiO3 probed by time-resolved x-ray diffraction," E. Zolotoyabko, J. P. Quintana, D. J. Towner, B. H. Hoerman and B. W. Wessels, Ferroelectrics 290 115-124 (2003).
"The electro-optic properties of epitaxial KTaxNb1-xO3 thin films," B. H. Hoerman, B. M. Nichols, and B. W. Wessels. Optics Comm., 219 (1) 377 (2003).
"Dielectric properties of plasma spray deposited BaTiO3 and Ba0.68Sr0.32TiO3 thick films," K. Ahn, B. W. Wessels, and S. Sampath, J. Mat. Research 18 (5) 1227 (2003).
"Polarisation-insensitive Si3N4 strip-loaded BaTiO3 thin-film waveguide with low propagation losses," with P. Tang, D. J. Towner, A. L. Meier, and B. W. Wessels, Electronics Letters 39 1651 (2003).
"Relative dielectric constant of epitaxial BaTiO3 thin films in the GHz frequency range," with T. Hamano, D. J. Towner, and B. W. Wessels, Appl. Phys. Letters, 83 5274-5276 (2003).
"Interfacial layer effects in BaSrTiO3 thick films prepared by plasma spray," K. Ahn, B. W. Wessels and S. Sampath, Proc. MRS (2003).
"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).
Recent Publications on III-V Semiconductors by Bruce W. Wessels
(supported by NASA NAG5-11457)
"On the Origin of the 2.8 eV Blue Emission in P-type GaN:Mg: A Time-resolved Photoluminescence Investigation," with F. Shahedipour and B.W. Wessels. J. Nitride Semicond. Res. 6, 12 (2001).
"Photoluminescence Studies of p-type GaN:Mg Co-doped with Oxygen," with R.Y. Korotkov, J.M. Gregie, and B.W. Wessels. MRS Proceedings, 639 (2001).
"Deep Level Formation in Undoped and Oxygen-Doped GaN," with J.M. Gregie, R.Y. Korotkov, and B.W. Wessels. MRS Proceedings, 639 (2001).
"Investigation of the Defect Structure of GaN Heavily Doped with Oxygen," with R. Y. Korotkov, F. Niu, J. M. Gregie, and B. W. Wessels. Physica B, 308-310 (2001).
"Mn-related Absorption and PL Bands in GaN Grown by Metal Organic Vapor Phase Epitaxy," with R. Y. Korotkov, J. M. Gregie, and B. W. Wessels. Physica B, 308-310 (2001).
"Progress in the Fabrication of GaN Photo-Cathodes," with M. P. Ulmer, B. W. Wessels, F. Shahedipour, R. Y. Korotkov, C. Joseph, and Tokuaki Nihashi. SPIE, 4288 246-253 (2001).
"Efficient GaN Photocathodes for Low-level Ultra-violet Signal Detection," with F. Shahedipour, M. P. Ulmer, B. W. Wessels, C. Joseph, and T. Nihashi. IEEE J. of Quant. Elec. 38 333 (2002).
"Defects observed by optical detection of electron paramagnetic resonance in electron-irradiated ptype GaN," L. S. Vlasenko, C. Bozdog, G. D. Watkins, F. Shahedipour, and B. W. Wessels. Physical Review B, 65 205202 (2002).
"Codoping of wide gap epitaxial III-nitride semiconductors," R. Y. Korotkov, J. M. Gregie, and B. W. Wessels. Opto-Electron. Rev. 10 (4) 243 (2002).
"Acceptors in undoped GaN studied by transient photoluminescence," R. Y. Korotkov, M. A. Reshchikov, and B. W. Wessels, Physica B 325 1 (2003).
"GaN Photocathodes for UV Detection and Imaging," with O. H. W. Siegmund, A. S. Tremsin, A. Martin, J. Malloy, M. Ulmer, and B. W. Wessels, Proc. SPIE, 5164, 2003.
"Investigation of the blue emission band in compensated GaN:Mg co-doped with Si," B. Han, J. M. Gregie and B. W. Wessels. PRB 68 045205 (2003).
"Investigation of deep-level luminescence in In0.07Ga0.93N:Mg," with B. Han, M. P. Ulmer, and B. W. Wessels, Physica B, 340-342 470-474 (2003).
"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)
"Optical Study of GaN Doped with Mn Grown by Metal Organic Vapor Phase Epitaxy," with R.Y. Korotkov, J.M. Gregie, and B.W. Wessels. MRS Proceedings, 639 (2001).
"Optical Study of GaN:Mn co-doped with Mg grown by metalorganic vapor phase epitaxy," R. Y. Korotkov, J. M. Gregie, B. Han, B. W. Wessels. Physica B 308-310 (2001).
"Growth and Characterization of OMVPE Grown (In, Mn) As Diluted Magnetic Semiconductor," with A. J. Blattner, J. Lensch, and B. W. Wessels. J. Electronic Materials, 30, (11) 1408-1411 (2001).
"Optical Properties of the deep Mn acceptor in GaN:Mn", with R. Y. Korotkov, J. M. Gregie, and B. W. Wessels. Appl. Phys. Lett., 50 No. 10, 1731-1733 (2002).
"Ferromagnetism in (In,Mn)As Diluted Magnetic Semiconductor Thin Films Grown by Metalorganic Vapor Phase Epitaxy," A. J. Blattner and B. W. Wessels. JVSTB 20 (4) 1582 (2002).
"Ferromagnetism in (In,Mn)As Diluted Magnetic Semiconductor Thin Films Grown by Metalorganic Vapor Phase Epitaxy," A. J. Blattner and B. W. Wessels. Applied Surface Science, 221 155-159 (2003).
"Origin of room temperature ferromagnetism in homogenous (In,Mn)As thin films," A. J. Blattner, P. L. Prabhumirashi, V. P. Dravid, and B. W. Wessels, J. of Crystal Growth 259 8-11 (2003).
"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.
"Electronic properties of Mn acceptors in (In,Mn)As grown by metalorganic vapor phase epitaxy," with S. J. May, A. J. Blattner, and B. W. Wessels, Physica B, 340-342, 870-873 (2003).
"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).