FUNCTIONAL HYBRID NANOMATERIALS

Synthesis of 2D materials, graphene, SWNTs, NT Arrays, NW’s, NP’s or thin films by CVD, Laser Vaporization, and PLD with in situ diagnostics

  • Thermal CVD of 2D materials including graphene, metal chalcogenides and 1D materials including SWNT, MWNT, vertically aligned nanotube arrays (VANTAs) on substrates
    Several CVD systems are available:
      • CVD system in a 3"-i.d. tube furnace (1200°C) with pressures down to ~ 1 Torr and fast-acting electro-pneumatic valves for switching source gases; integrated time-resolved reflectivity diagnostics and remote video imaging of growth dynamics. The system is in proximity of tunable ns-lasers for laser diagnostics of CVD processes, or for combined laser-CVD (e.g. for doping of nanotubes during CVD growth, or laser-generation of catalyst nanoparticles for CVD, etc.).
      • Thermal CVD of single and multiwall carbon nanotubes, nanotube arrays, and nanotube patterns at atmospheric pressure and flow.
      • Metal Chalcogenide CVD systems – Several systems specific to different materials (such as GaSe, MoS2, MoSe2, WS2, WSe2) specialize in the growth of 2D crystals by vapor transport growth from mixed evaporated powders.
    • Time-resolved reflectivity (TRR) of nanomaterial growth kinetics by CVD
      For aligned nanotube arrays, utilizes stabilized HeNe laser beam reflectivity Fabry-Perot interference oscillations and attenuation to directly measure the height of vertically-aligned nanostructure arrays during growth – for growth rate, catalyst assessment.  
    • ns-Laser Vaporization Synthesis of SWNTs, NWs, NPs
      SWNTs and nanowires are produced by pulsed Nd:YAG laser-irradiation (30 Hz, Q-switched or free-running) of composite pellets in a 2" tube furnace with variable pressure control. Excimer laser ablation of materials into variable pressure background gases is used for nanoparticle generation in proximity of ns-laser diagnostics.
    • fs-laser synthesis of metal or alloy nanoparticles by through-thin-film ablation – nm’s thin metal films deposited on transparent substrates are ablated by single fs-laser pulses.  Gated ICCD imaging or Rayleigh scattering diagnostics are used to observe the nanoparticle cloud in vacuum or background gases.  Samples are collected on TEM grids for analysis.
    • High-power ms-laser vaporization bulk production of nanomaterials
      SWNH (single-wall carbon nanohorns), nanotubes, nanoparticles and nanowires in grams quantities are produced by robotically-scanned 600W Nd:YAG laser-irradiation (1064 nm) of targets at controlled pressure in various atmospheres (including CVD gases) at <1200°C inside a 3" tube furnace. Rapid sampling capability (located outside of the CNMS).

Oxide Thin Film Pulsed-Laser Deposition – Complex Heterostructures with high-pressure RHEED

  • Oxide thin film and complex oxide heterostructure PLD
    Oxide thin films and complex oxide superlattice growth by pulsed-laser deposition (including magnetic, ferroelectric, superconducting materials; strain-engineered heterostructures) with in-situ high-pressure RHEED for atomic-layer control.
  • Complex heterostructures combining PLD, RF-sputtering, and laser heating
    Growth of thin films of oxide and metallic compounds combining oxide PLD and RF sputtering to create composites and superlattice heterostructures. This growth system incorporates laser heating, and pressure control to rapidly change growth conditions, along with in-situ RHEED.
  • Oxide Target Synthesis
    Standard facilities for milling, drying, pressing, and sintering of oxide materials, to prepare PLD targets.

Laser Processing and Interactions with Materials

  • Laser processing of materials under controlled atmospheres
    High-power pulsed or CW (600W) Nd:YAG (1064 nm) for rapid thermal processing, or pulsed CVD growth in hydrocarbon gas atmospheres.  In addition, pulsed nanosecond or femtosecond irradiation of materials for laser cutting, thinning, patterning, reduction, nanostructuring (SERS, LIPSS), or surface modification with X-Y-Z control.
  • Laser induced forward transfer
  • Gated ICCD imaging and spectroscopy of laser vaporization processes
    Intensified CCD-array photography (5-ns resolution) and intensified, gated diode-array spectroscopy of laser interactions and laser ablation processes in controlled atmospheres. Secondary pulsed probe laser illumination for LIF, LII, LIP, scattering, and broadband OAS.

Wet/Dry Processing and Assembly of Organic, Inorganic, and Hybrid Materials and Devices

  • Photolithographic-, E-beam-, FIB-Patterning/Wiring of Nanomaterials for Devices
    (Through the Nanofabrication Research Laboratory) Processing of nanomaterials including spin-coating, dielectrophoretic deposition, etc. combined with photo- and e-beam lithographic techniques and FIB electrode placement for the addressing of nanomaterials as prototype devices.
  • Controlled atmosphere dual glove box evaporator system for inorganic films and organic electronics
    An MBraun Labmaster double glove box system with integrated vacuum deposition chamber (Angstrom Amod e-beam and thermal evaporator) and spin coater (Specialty Coating Systems Model SCS G3) is available for physical vapor deposition of metals and small-molecule organics and for spin coating of polymers in a clean, inert environment. Thermal chambers have six sources, including two RADAK sources for small-molecule deposition with co-deposition capability, which enable multilayer deposition, gradient and doping film deposition at controlled substrate temperatures (RT to 400°C). The system is also equipped for computer-controlled e-beam deposition with four pocket electron-beam sources and two thermal sources for high melting point metals and inorganic compound thin film deposition. A 400°C vacuum oven is mounted to one end of the glove box. The system has various shadow masks for patterning electrodes for various organic electronic devices including OFETs, OLEDs, OPVs, and spin valves. The system enables the assembly of organic and inorganic multilayer thin films with Ångstrom thickness resolution for organic electronic devices.
  • Sonospray deposition of nanomaterials and organics
    Computer-controlled sono-spray deposition of nano materials, polymers, and nano composites from solutions and suspensions for uniform or patterned deposition on small or large areas (up to 1ft x 1ft) with minimum feature size of 1.5 mm. The system enables multilayer deposition on various substrates, including polymers, while controlling the substrate temperature (up to 180C). A micro-syringe pump feeds a solution allowing deposition from small (<10ml) volumes of solution and a dual-syringe configuration allows simultaneous deposition from two different solutions with variable ratio. The system is also equipped with a sono-syringe, to prevent precipitation of material during deposition (min required volume 20ml).
  • Hybrid Organic/Inorganic Perovskite Films and Device Fabrication
    Formed by solution phase synthesis techniques and spin coating or Sonospray deposition.  Associated layer by layer deposition, processing, and electrode application.
  • 2D Crystal Stamping
    A microscope based setup to transfer exfoliated or CVD-grown layers of 2D materials from polymer-coated ribbons is available, allowing the stamp-fabrication of 2D heterostructures.

Optical Characterization and Laser Spectroscopy of Nanomaterials

  • Ultrafast femtosecond laser pump-probe spectroscopy of nanomaterials and composites
    A Coherent Legend Titanium sapphire based amplifier, providing pulses centered at 800 nm with ~2 mJ/pulse, 45 fs short durations, and operating at 1 kHz repetition rate, is used to pump an optical parametric amplifier (OPA), and a small portion is used to generate spectrally broad white light continuum (450-950 nm).  The tunable output of the OPA (400-2500nm) is used as pump, and the white light continuum is used as probe.  This pump probe setup is capable of studying samples in liquid and solid phases.  The spatial resolution in transmission mode, is ~ micron, and in reflection mode is ~10 microns.  In both modes the temporal resolution is ~ 45 fs providing with sub-milli-OD absorbance sensitivity at 500Hz acquisition rate.
  • Ultrahigh resolution fixed/tunable Raman (micro/macro) spectroscopy (0.25 – 1.6 µm) with cryogenic stage and scanning capability
    Ultrahigh-resolution JY T-64000 monochromator permits Raman spectroscopy at several fixed excitation wavelengths > 10 cm-1 along with cryogenic (liquid He) temperature capabilities and X-Y scanning.  A tunable ps laser-based OPO permits exciation at any wavelength (0.25 – 1.6 µm) with scattered wavelengths beyond 50 cm-1 of laser line). Also, tunable CW Ti:Sapphire laser for 780-950 nm excitation wavelengths. Inverted microscope with XY stage, and standard microscope with XY and piezo-Z stages. 
  • Raman characterization of carbon nanotubes, oxides, polymers, 2D materials
    Conventional Renishaw confocal micro-Raman spectroscopy setup using 2 fixed wavelengths (785 nm, 633 nm) and 3-dim rotation/translation stages. X-Y mapping.
  • In situ Raman spectroscopy at <1500°C: CVD, annealing, electrochemistry
    Linkam hot stage annealing and growth chamber permits in situ dynamics of SWNT growth or processing under Raman microscope. Electrochemical cell under Raman microscope.
  • Combined Raman, Photoluminescence, Absorbance, PL Lifetime Microscopy for 2D materials
    Dual inverted/upright homebuilt Raman, PL, and absorption microscopy setup devoted to 2D materials still in development.  405, 532 nm excitations.  Raman and PL mapping.  Lamp-based absorbance. Time-correlated single photon counting PL lifetimes. 
  • Tunable (0.25 – 1.6 µm) fs/ps laser system (nJ @ 80 MHz)
    Ti:Sapphire-based oscillator coupled to second- and third-harmonic generator crystals, along with OPO, may be run in either fs or ps mode. Coupled to confocal microscope with XYZ control for Raman spectroscopy or fluorescence measurements Provides nj/ps-pulse at 80MHz to avoid damage to nanostructures.
  • Tunable (0.3 – 2.6 µm) High energy, Ultrashort, fs laser system (2.5 mJ @ 1 kz, 40 fs)
    Ti:Sapphire-based amplifier used to pump a high energy non-collinear OPA (accepts > 2mJ/pulse). A portion of the fundamental beam (800 nm) is used to generate a white light supercontinuum for spectrally-resolved pump-probe techniques. System also applicable to other nonlinear spectroscopies or fs laser processing (ablation, annealing, machining, polymerization, etc.).
  • Tunable (0.22 – 1.8 µm) ns laser system (mJ @ 10Hz)
    Tunable Nd:YAG –pumped OPO laser provides high pulse energies for in situ spectroscopic experiments (e.g. LIF) of nanomaterial growth environments, laser ablation synthesis, or nanomaterial luminescence.
  • UV-VIS-NIR Characterization of Nanomaterials by Absorption Spectroscopy
    Measurement and analysis of optical absorption spectra to investigate electronic energy levels and dispersion of solubilized nanomaterials in cuvettes, or materials on substrates.  Cary 5000. 
  • UV-VIS-NIR Fluorometry with remote fiber probing of liquids/surfaces
    Utilizes dispersed Xe lamp to excite fluorescence of solubilized or solid specimens. Two spectrometers (UV-VIS, and NIR) under computer control record fluorescence spectra. Excitation wavelength can be scanned to provide complete fluorescence maps vs. excitation wavelength. Fiber probe permits remote sampling of liquids or solid surfaces.

Electrical and Optoelectronic Characterization of Nanomaterials

  • Semiconductor parameter analyzer, cryogenic probe station, and both DC and AC characterization systems
    (Contact Ilia Ivanov for more details).
  • AC impedance spectroscopy system based on the Zahner analyzer IM6 supports traditional electrochemical investigations like impedance measurements (10 µHz-8 MHz, 10 Ohm-1 GOhm), cyclic voltammetry, corrosion, current-potential curves, etc. with modeling software by THALES. AC-amplitude range 1 mV to 1 V. Impedance range 10 mOhm to 1 GOhm (+/-1 dB).
  • Special configuration Zahner controlled intensity modulated photospectroscopy capability enables dynamic photo-electric investigations including mixed photo electric transfer functions on photo-sensitive objects (e.g. photovoltaic materials).
  • Intensity modulated (LED based: UV-NIR) Photocurrent/Photovoltage measurement (solid, liquid samples).
    (Contact Ilia Ivanov for more details).
  • Optical characterization (UV-NIR): absorbance, transmittance, reflectance (diffuse and specular), PL, Raman under electrical excitation. Cary 5000 with special attachments.Calibrated OLED efficiency measurement system (including angular light distribution).
  • Spectral photoresponse and calibrated PV efficiency measurement system
    (Contact Ilia Ivanov for more details).
  • Spectroelectrochemical Characterization of Nanomaterials and Composites
    Combined electrochemical measurements during spectrophotometry. Investigations of reduction-oxidation reactions; nA sensitivity using Faraday cage with three-electrode stand.
  • Environmental Test Chamber with Electrical and Optical Access
    A windowed vacuum chamber enclosed in an atmospherically-controlled enclosure with electrical feedthroughs and associated electronics to perform electrical measurements on samples and devices with controllable temperature, humidity, oxygen level. Labview-based Multimode Sensing (electrical, optical, weight) of thin films to programmable environmental exposure. Weight change using vacuum compatible quartz crystal microbalance. Optical windows permit optical excitation and observation of the samples.

 

Capabilities provided by other CNMS groups