Wright Center for Photovoltaics Innovation and Commercialization



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The University of Toledo

Res & Tech Complex 1

2600 Dorr St.

Toledo, OH  43606


Material Characterization


Profilometer (Dektak 150)
Resistivity and Sheet Resistance (4-point probe)
Solar Simulator
External Quantum Efficiency
UV-VIS-NIR spectrophotometer
Fourier Transform Infrared Spectroscopy (FTIR)
Ellipsometry (IR-Vase, Mapping, V-Vase)
Atomic Force Microscopy (Veeco NanoScope V)
Van der Pauw Hall Effect
Auger Electron Spectrophotometer (Perkin-Elmer PHI600)
Thermogravimetric Analysis (Ta Instruments Q600 TGA)
Time-Resolved Photoluminescence
Raman Spectrophotometer and FT- Photoluminescence Spectrometer
Laser Beam Induced Current (LBIC) and Laser Beam Induced Voltage (LBIV)
Temperature Programmed Desorption (TPD)
PAR 263 Potentiostat/Galvanostat
Solar Flash Table (Spire SPI-Sun Simulator 4800)
Solstice Transient Absorption Laser System
Back to Equipment Category List



Profilometer (Dektak 150)  Dektak150  A profilometer measures the vertical depth of a material across a horizontal length. A diamond stylus is transverse laterally across the sample with a specified distance and contact force. The stylus moves vertically with the surface variations, and the displacement can be measured as a function of position. This equipment can be employed to measure etch depth, deposited film thickness, and surface roughness.   TOP OF PAGE



Resistivity and Sheet Resistance (4-point probe)  4 point probe  4-point probe measures the sheet resistance of a thin film. It is an electrical impedance measuring technique that has a pair of current-carrying (driving force) and voltage-sensing (sensing) contacts that is more accurate than the traditional two terminal methods, because it eliminates the impedance contribution of the wiring and the contact resistances.  A current is supplied by a pair of force connections, and a pair of sense connections.  TOP OF PAGE  



Solar Simulator (IV Curve System)  SolarSimulator  Our solar simulator is a Class A Solar Simulator, so it maintains a exceptionally tight uniformity, output stability, and spectral match. The solar simulator provides repeatable light conditions, equal to ¡°one sun¡±. The device uses a xenon arc lamp with an ellipsoidal mirror, filtering, and beam collimation. The cell (or diode) is connected to a multi-meter and a voltage sweep occurs. That is then plotted verses the current produced.  TOP OF PAGE  



External Quantum Efficiency (EQE) System  EQE system  External Quantum Efficiency (EQE) is known as the ratio of the number of photons (of a given energy shining on the solar cell) to the number of charge carriers collected. It reports the response of a photovoltaic cell to the precise wavelengths in the spectrum of light shining on the cell. For example, if all of the photons of a certain wavelength were collected, the quantum efficiency would be 100%.  TOP OF PAGE  



UV-VIS-NIR Spectrophotometer (Lamda 1050)  spectrophotometer  The Spectrophotometer uses a photometer to measure the intensity of light as a function of the source wavelength.It evaluates the sample with   visible   light, near-ultraviolet, and near-infrared (or any combination) and ranges for 190nm to 3300nm. Our double beam spectrophotometer compares the light intensity between two paths (one as a reference and the other the test). It measures the transmission of light through a sample, reflection off of the sample (diffuse and specular), and pseudo absorption.  TOP OF PAGE  



Fourier Transform Infrared Spectroscopy (FTIR)  FTIR  Thermo Scientific Nicolet is FT-IR spectrometer excels at rugged, precise, fast-paced operation yet simplifies laboratory data collection to its most steps by loading the sample and generates the spectrum. The Nicolet FT-IR spectrometer is a complete infrared spectroscopy system for routine analytical needs. The Nicolet delivers the highest confidence in the verification and identification of materials and is designed for maximum assurance in its ability to sample and solve challenging problems with a minimal investment in time.   TOP OF PAGE  



Ellipsometry (IR-Vase, Mapping, V-Vase)  Ellipsometry is a non-destructive optical technique for investigating the dielectric properties of thin films. The technique utilities a beam of polarized light at incident on a sample, and the change in the polarization state and amplitude of that light beam induced by interaction with the sample is determined. Ellipsometry can be used to characterize composition, roughness, thickness (depth), crystalline nature, doping concentration, electrical conductivity and other material properties. It is very sensitive to the change in the optical response of incident radiation that interacts with the material being investigated.   IRVase  The IR-VASE Ellipsometer is a rotating compensator ellipsometer (RCE) for ex-situ SE data acquisition in the spectral range of 1.7 to 30 micron ( 333 cm-1 to 6000 cm-1). A robust instrument to characterize the free carrier behavior in metal and degenerate semiconductors like TCOs.   TOP OF PAGE   mapping_ellipsometer  The Mapping Ellipsometer uses M2000 DI ellipsometer which is again RCE type. Spectral range is quite large, from 0.6 eV to 6.5 eV. Very useful to characterize the inter-band optical behavior of semiconductors as well as low bandgap dielectrics.  TOP OF PAGE   VVase_Ellipsometer  The V-VASE is a rotating analyzer ellipsometer (RAE), equipped with auto retarder option which makes superior to other ellipsometers mainly due to its capacity to measure the ellipsometric parameter "delta" without ambiguity of trouble regions of other designs. This instrument is also equipped with cryostat which makes possible to measure samples at temperature ranging from 4.2 to 700 Kelvin.  TOP OF PAGE  



Atomic Force Microscopy (Veeco NanoScope V)  AFM  Atomic force microscopy (AFM) is a very high-resolution type of scanning probe microscopy, with demonstrated resolution on the order of fractions of a nanometer. The information is gathered by scanning the surface with a mechanical probe, through which process a surface morphology picture will be constructed.
The AFM consists of a cantilever with a sharp tip (probe) that is used to scan the specimen surface. The cantilever is typically silicon or silicon nitride with a tip radius of curvature on the order of nanometers. When the tip is brought into proximity of a sample surface, forces between the tip and the sample lead to a deflection of the cantilever according to Hooke's law. The deflection is measured using a laser spot reflected from the top surface of the cantilever into an array of photodiodes.  TOP OF PAGE



Van der Pauw Hall Effect Measurement System  VanderPauwHallEffect  The MMR Hall Effect Measurement System provides automatic measurements of the electrical properties of semiconductor materials using the van der Pauw measurement technique. By measuring the Hall voltage generated by a current-carrying conductor placed in a magnetic field, properties of the material, such as sheet resistance, doping type, carrier density, and mobility of majority carrier, can be calculated. The variable temperature Hall Effect measurement with temperature ranging from 70 K to 500 K is feasible.   TOP OF PAGE  



Auger Electron Spectrophotometer (Perkin-Elmer PHI600)   The auger electron spectrophotometer (AES) is used specifically to study of surfaces in the area of material science. Measurement is made by analyzing energetic electrons emitted from excited atoms after a series of internal relaxation events. AES is surface sensitive due to electrons having a short mean free path in a solid and is therefore localized to a few nanometers of the target surface.   TOP OF PAGE Auger_Spectrophotometer  



Thermogravimetric Analysis (Ta Instruments Q600 TGA)  TGA  The TA Q600 is capable of simultaneously performing thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) on small sample up to 1300 C. TGA measures mass of a sample as it is heated and can be used to determine the decomposition temperature. DSC measures the energy absorbed/released during heating and can be used to determine the latent heat of a phase change or the temperature at which it occurs.   TOP OF PAGE  



Photoluminescence   Photoluminescence characterization of semiconducting materials begins with by illuminating the sample with light of energy larger than the material band gap. Should the excited carriers recombine radiatively, the photoluminescence spectra reveals the energy transitions associated with the recombination pathway. Depending on the material, these transitions can be Band-to-Band, Trap-Assisted, or Donor-Acceptor Pair transitions. The Band-to-Band transition indicates the materials band gap while the ratios of photoluminescence intensities are a measure of material quality.  TOP OF PAGE  



Time-Resolved Photoluminescence    TRPL Time-Resolved Photoluminescence (TRPL), also referred to as Time Correlated Single Photon Counting (TCSPC), provides a non-destructive measurement of the mean carrier lifetime in a material or thin-film stack. An ultrafast laser pulse is used to excite the material and while advanced electronics record the time delay between excitation and the detection of an emitted photon. Longer carrier lifetime is a very important parameter, as it increases the probability of charges contributing to photo-current in solar cells.   TOP OF PAGE  



Raman Spectrophotometer and FT- Photoluminescence Spectrometer    RamanSpectrophotometer Thermo Scientific Nicolet NXR FT-Raman Spectrometers are the perfect complement to an FT-IR. The Thermo Scientific family of Nicolet NXR FT-Raman spectrometers are highly versatile instruments designed to meet the needs of a wide range of applications. The Nicolet NXR FT-Raman offers fluorescence-free sampling of organic materials enabling high-quality Raman measurements of many highly fluorescent samples. The Nicolet NXR FT-Raman spectrometers combine exceptionally high performance with a wide range of sample accessories to create a system that is capable of running everything from bulk samples to microscopic samples, either one sample at a time or many at a time. OMNIC Array provides for automated data collection and analysis of array based sample formats such as well-plates. The laser used to excite the sample is of wavelength of 976 nm and able to excite the semiconducting SWNT. It is the important tool for SWNT characterization.
The customization of a commercially available FT Raman system allows for development of the FT-PLE apparatus. No commercial FT-based NIR fluorimeters with tunable excitation are available. We utilized a Thermo- Nicolet FT- Raman spectrometer that contains a 1064 nm diode laser for excitation and a liquid nitrogen cooled germanium detector for measuring sample emission from 825 nm to 1700 nm.
The spectrometer is used for detection of SWNTs photoluminescence (PL) with tunable excitation was developed. The instrument offers rapid, robust, and sensitive detection, and was used to perform low-temperature PL measurements and confirm predictions that SWNT recombination kinetics are influenced by multiple excitonic bands, including a dark lower state. Toward the goal of obtaining a single nanotube type, the spectrometer’s speed advantage has allowed for the study the kinetics of PL quenching as isolated nanotubes re-bundle in suspension.   TOP OF PAGE



Laser Beam Induced Current (LBIC) and Laser Beam Induced Voltage (LBIV)    LBIC_LBIV Time-Resolved Photoluminescence (TRPL), also referred to as Time Correlated Single Photon Counting (TCSPC), provides a non-destructive measurement of the mean carrier lifetime in a material or thin-film stack. An ultrafast laser pulse is used to excite the material and while advanced electronics record the time delay between excitation and the detection of an emitted photon. Longer carrier lifetime is a very important parameter, as it increases the probability of charges contributing to photo-current in solar cells.   TOP OF PAGE  



Temperature Programmed Desorption (TPD)    TPD Temperature Programmed Desorption (TPD) involves heating a testing sample while contained in a vacuum and simultaneously detecting the residual gas in the vacuum by means of a mass spectrometer. As the temperature rises, certain absorbed species (atoms, molecules, and etc.) will have enough energy to escape and will be detected as a rise in pressure for a certain mass. This technique is used for studying surface reactions and molecular adsorption on the surface. In our lab, quadrupole mass spectrometer (QMS) is used as the gas analyzer and the whole process is carried out under computer control with quasi-simultaneous monitoring of a large number of possible products.   TOP OF PAGE  



PAR 263 Potentiostat/Galvanostat    PAR263 The PAR 263 is a versatile instrument capable of running many electrochemistry experiments. UT has coupled it with a three electrode cell for cyclic voltammetry measurements capable of operating in the laboratory and inside an anaerobic chamber. The system has also been used for electroplating devices.   TOP OF PAGE  



Solar Flash Table (Spire SPI-Sun Simulator 4800)    SolarTable The Spire Solar Flash Table that is able to test large photovoltaic panels by illumination approximating natural sunlight. This type solar simulator is the flashed simulator which uses flash tubes with typical durations of several milliseconds. This type of equipment is often used to prevent unnecessary heat build-up in the device under test.   TOP OF PAGE  



Solstice Transient Absorption Laser System    SolsticeTransientAbsorptionLaserSystem The transient absorption (TA) system consists of a Solstice Laser system from Spectra Physics. The Solstice output is a ~100 fs laser pulse centered at 798 nm, with a repition rate of 4 KHz, and pulse energy of 925 μj. This is then sent into a pair of TOPAS optical parametric amplifiers, so as to tune the wavelengths of the pump and probe pulses independently. Thus we have TA capabilities from 270 nm to 3 μm for the pump, and from 300 nm out to 9 μm for the probe. This allows for the investigation of the ultrafast responses of a wide variety of materials over a wide spectral range.   TOP OF PAGE  



Last Updated: 3/23/15