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Title: Liquid crystal terahertz phase shifters with functional indium-tin-oxide nanostructures for biasing and alignment

Abstract

Indium Tin Oxide (ITO) nanowhiskers (NWhs) obliquely evaporated by electron-beam glancing-angle deposition can serve simultaneously as transparent electrodes and alignment layer for liquid crystal (LC) devices in the terahertz (THz) frequency range. To demonstrate, we constructed a THz LC phase shifter with ITO NWhs. Phase shift exceeding π/2 at 1.0 THz was achieved in a ∼517 μm-thick cell. The phase shifter exhibits high transmittance (∼78%). The driving voltage required for quarter-wave operation is as low as 5.66 V (rms), compatible with complementary metal-oxide-semiconductor (CMOS) and thin-film transistor (TFT) technologies.

Authors:
 [1];  [2];  [3];  [4];  [5];  [1];  [6]
  1. Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China)
  2. (United States)
  3. Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan (China)
  4. Department of Electrophysics, National Chiao Tung University, Hsinchu 30078, Taiwan (China)
  5. Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China)
  6. (China)
Publication Date:
OSTI Identifier:
22261551
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 14; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALIGNMENT; CURIUM OXIDES; ELECTRON BEAMS; INDIUM; LIQUID CRYSTALS; NANOSTRUCTURES; PHASE SHIFT; SEMICONDUCTOR MATERIALS; THIN FILMS; TIN OXIDES; TRANSISTORS

Citation Formats

Yang, Chan-Shan, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, Tang, Tsung-Ta, Pan, Ru-Pin, Yu, Peichen, Pan, Ci-Ling, E-mail: clpan@phys.nthu.edu.tw, and Frontier Research Center on Fundamental and Applied Science of Matters, Hsinchu 30013, Taiwan. Liquid crystal terahertz phase shifters with functional indium-tin-oxide nanostructures for biasing and alignment. United States: N. p., 2014. Web. doi:10.1063/1.4871255.
Yang, Chan-Shan, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, Tang, Tsung-Ta, Pan, Ru-Pin, Yu, Peichen, Pan, Ci-Ling, E-mail: clpan@phys.nthu.edu.tw, & Frontier Research Center on Fundamental and Applied Science of Matters, Hsinchu 30013, Taiwan. Liquid crystal terahertz phase shifters with functional indium-tin-oxide nanostructures for biasing and alignment. United States. doi:10.1063/1.4871255.
Yang, Chan-Shan, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, Tang, Tsung-Ta, Pan, Ru-Pin, Yu, Peichen, Pan, Ci-Ling, E-mail: clpan@phys.nthu.edu.tw, and Frontier Research Center on Fundamental and Applied Science of Matters, Hsinchu 30013, Taiwan. Mon . "Liquid crystal terahertz phase shifters with functional indium-tin-oxide nanostructures for biasing and alignment". United States. doi:10.1063/1.4871255.
@article{osti_22261551,
title = {Liquid crystal terahertz phase shifters with functional indium-tin-oxide nanostructures for biasing and alignment},
author = {Yang, Chan-Shan and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 and Tang, Tsung-Ta and Pan, Ru-Pin and Yu, Peichen and Pan, Ci-Ling, E-mail: clpan@phys.nthu.edu.tw and Frontier Research Center on Fundamental and Applied Science of Matters, Hsinchu 30013, Taiwan},
abstractNote = {Indium Tin Oxide (ITO) nanowhiskers (NWhs) obliquely evaporated by electron-beam glancing-angle deposition can serve simultaneously as transparent electrodes and alignment layer for liquid crystal (LC) devices in the terahertz (THz) frequency range. To demonstrate, we constructed a THz LC phase shifter with ITO NWhs. Phase shift exceeding π/2 at 1.0 THz was achieved in a ∼517 μm-thick cell. The phase shifter exhibits high transmittance (∼78%). The driving voltage required for quarter-wave operation is as low as 5.66 V (rms), compatible with complementary metal-oxide-semiconductor (CMOS) and thin-film transistor (TFT) technologies.},
doi = {10.1063/1.4871255},
journal = {Applied Physics Letters},
number = 14,
volume = 104,
place = {United States},
year = {Mon Apr 07 00:00:00 EDT 2014},
month = {Mon Apr 07 00:00:00 EDT 2014}
}
  • We investigated the interfacial electronic structures of Al/adenine/indium-tin-oxide (ITO) and Al/thymine/ITO using in situ ultraviolet and x-ray photoemission spectroscopy and density functional theory calculations. Adenine shows both an interface dipole and level bending, whereas thymine shows only an interface dipole in contact with ITO. In addition, thymine possesses a larger ionization energy than adenine. These are understood with delocalized {pi} states confirmed with theoretical calculations. For the interface between nucleobases and Al, both nucleobases show a prominent reduction of the electron injection barrier from Al to each base in accordance with a downward level shift.
  • Indium tin oxide (ITO) nanostructures were successfully deposited on glass substrate by pulsed laser ablation in argon gas at 250 deg. C. Microstructural changes were observed in the argon gas pressure between 30 to 50 mTorr. The as-grown, nanostructured ITO exhibit In{sub 2}O{sub 3} bixbyite structure orientated at <111> direction. At the initial stage of growth, there was a large number of nucleation sites detected which eventually evolved into needle-like branches. The presence of spheres at the tip of these branches indicates that these nanostructured ITO were likely governed by vapor-liquid-solid (VLS) growth mechanism.
  • Origin of unexpected defect engineered room-temperature ferromagnetism observed in tin-doped indium oxide (ITO) nanostructures (Nanowires, Nano-combs) and nanocrystalline thin films fabricated by pulsed laser deposition has been investigated. It is found that the ITO nanostructures prepared under argon environment exhibit strongest ferromagnetic signature as compared to that nanocrystalline thin films grown at oxygen. The evidence of singly ionized oxygen vacancy (V{sub 0}{sup +}) defects, obtained from various spectroscopic measurements, suggests that such V{sub 0}{sup +} defects are mainly responsible for the intrinsic ferromagnetic ordering. The exchange interaction of the defects provides extensive opportunity to tune the room-temperature d{sup 0} ferromagnetismmore » and optical properties of ITOs.« less
  • The electronic structure evolution and energy level alignment have been investigated at interfaces comprising fullerene (C{sub 60})/4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl) benzenamine] (TAPC)/ molybdenum oxide (MoO{sub x})/ indium tin oxide with ultraviolet photoemission spectroscopy and inverse photoemission spectroscopy. With deposition of TAPC upon MoO{sub x}, a dipole of 1.58 eV was formed at the TAPC/MoO{sub x} interface due to electron transfer from TAPC to MoO{sub x}. The highest occupied molecular orbital (HOMO) onset of TAPC was pinned closed to the Fermi level, leading to a p-doped region and thus increasing the carrier concentration at the very interface. The downward band bending and the resulting built-inmore » field in TAPC were favorable for the hole transfer toward the TAPC/MoO{sub x} interface. The rigid downward shift of energy levels of TAPC indicated no significant interface chemistry at the interface. With subsequent deposition of C{sub 60} on TAPC, a dipole of 0.27 eV was observed at the C{sub 60}/TAPC heterojunction due to the electron transfer from TAPC to C{sub 60}. This led to a drop of the HOMO of TAPC near the C{sub 60}/TAPC interface, and hence further enhanced the band bending in TAPC. The band bending behavior was also observed in C{sub 60}, similarly creating a built-in field in C{sub 60} film and improving the electron transfer away from the C{sub 60}/TAPC interface. It can be deduced from the interface analysis that a promising maximum open circuit voltage of 1.5 eV is achievable in C{sub 60}/TAPC-based organic photovoltaic cells.« less
  • The preparation of indium-tin-oxide (ITO)/p-InP and ITO/p-GaAs solar cells via ion-beam deposition, rf sputtering, and magnetron sputtering of ITO onto single-crystal InP and GaAs substrates is described. The properties of these solar cells are strongly affected by the fabrication conditions and are related to chemical modifications of the junctions. The solar power conversion efficiencies at air mass 2 of ITO/p-GaAs and ITO/p-InP solar cells are < or =5 and < or =14.4%, respectively.