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Ellisometer

The M-2000 spectroscopic ellipsometer by Woollam is engineered to meet the diverse demands of thin film characterization. An advanced optical design, wide spectral range, and fast data acquisition combine in an extremely powerful and versatile tool. Measurements covers the spectral range from deep ultraviolet (193 nm) to near infrared (1690 nm). The use of a CCD (Charge Coupled Device) detector allows simultaneous measurement of hundreds of wavelengths.

The system is also equipped with an automatic mapping stage, able to automatically mapping films up to 8" in diameter.

The M-2000 is commonly used to measure thin film thickness and optical constants of materials. It is sensitive to less than a monolayer of material (sub-nm) on a surface.

The ellipsometer is mainly linked to the atomic layer deposition (ALD) machine installed in the same laboratory, and that is mainly used for synthesizing materials for water treatment. Anyway the ellipsometer can be used for any research activities.

Spectrophotometer

The LAMBDA 45 UV/Vis spectrophotometer is equipped with an halogen lamp for measurements in the VIS region and a deuterium lamp for measurements in the UV region. It operates in a range of 190 - 1100 nm with a resolution of ± 0.1 nm. The bandwidth is in the range of 0.5 - 4 nm, with a speed scan between 7.5 and 2880 nm/min.

LAMBDA 45 is a spectrophotometer for measurements of liquids samples, regulatory tests requiring variable resolution, and highly light-scattering samples. The additional pre-monochromator reduces stray light by a factor of 2, providing optimum performance for turbid and light-scattering samples, such as some biological solutions and suspensions.

The spectrophotometer can operate in scanning mode, wavelength program, time-drive, rate, quant and scanning quant.

The spectrophotometer is particularly suited to investigate the photocatalytic properties of nanostructures by the degradation of organic dyes and DNA/RNA analysis, the detection of biomolecules and to evaluate the concentration of bacterial samples.

30 KV Field Emission Scanning Electron Microscope

A Gemini Field Emission Scanning Electron Microscope (FE-SEM) Carl Zeiss SUPRA™ 25 is equipped with  (i) an EDAX Energy Dispersive X-Rays (EDX) detector, (ii) a Gemini multi-mode scanning Transmission Electron Microscope (STEM) detection system and (iii) a Gatan MonoCL4™ system for  cathodoluminescence (CL) microscopy.

SEM Resolution: 1.7 nm @ 15 kV

                            3.5 nm @ 1 kV

Acceleration Voltage: 0.5 - 30 kV

Probe Current: 4 pA - 10 nA

Detectors: High efficiency In-lens detector

                 Secondary electrons detector

                 STEM detector

                 EDX microanalysis detector for imaging/mapping and X-Rays Spectroscopy

                 CL system for Panchromatic and Monochromatic imaging and Spectroscopy (Spectral response 185- 850 nm)

FE-SEM is used to investigate morphology, chemical and optical properties of thin films and nano powders.

 Optical Characterization Laboratory

The Optical characterization Laboratory is equipped for photo- and electro-luminescence measurements on thin films, liquids and powders. It is equipped with different excitation continuum laser sources:

  • HeCd (325 nm)
  • Ar (different lines in the 457-514.5 nm range)
  • Ti-sapphire (tunable In the wavelength range 700-1000 nm)

    and different devices for the detection of the luminescence signal:

  • Hamamatsu photomultiplier tube  for the UV and visible region
  • Infrared extended Hamamatsu photomultiplier
  • Ge detector for the near infrared region (from 800 to 1700 nm)
  • Hamamatsu InAs detector and Judson Technologies InSb detector for the infrared region (up to 3500 nm and 5500 nm, respectively)

    Time-resolved measurements using an acousto-optic modulator to modulate the laser and a Stanford Research multichannel scaler to acquire the signal with a time resolution of about 30 ns. 

  • A system for time-resolved photoluminescence measurements formed by an optical parametric oscillator (OPO) pumped by a ns Nd:YAG laser, a spectrograph with an intensified CCD and a linear InGaAs detector. With this setup it is possible to measure PL spectra by tuning the excitation wavelength in the 200-2000 nm range and to perform time resolved PL measurements with a time resolution of 10 ns.
  • An Oxford closed cycle He cryostat for low temperature measurements down to 10 K.

Different power supplies (both continuous and pulsed) for electroluminescence measurements.

Electrical Characterization Laboratory

The Electrical Measurements Laboratory is equipped with two probe stations connected to highly sensitive measurement instruments to characterize different electrical properties on semiconductor materials and devices, and the necessary equipment to carry out measurements of External and Internal Quantum Efficiency on solar cells.

Sheet resistance, carrier concentration and mobility, I-V measurements, in a wide range of temperature are performed by a BioRad HL5560 Hall effect system equipped with SpectrostatCF Oxford liquid helium cryostat and buffer amplifier.

BioRad HL5560 specifications:

Minimum carrier density: 2x1011cm-2.

Hall Mobility range: 0.1÷3x103cm2/Vs.

Sheet resistance range: 0.5÷1x105Ω/sq.

Contact resistance lower than 105Ω.

Temperature range: 3.5÷500 K.

Low current (10-12 A) to measure very high resistances (1012 Ω/sq).

C-V, IG-VGS, ID-VGS, flat-band voltage, threshold voltage, transconductance, dielectric thickness, doping concentration, effective charges, interface state, defect density, conduction mechanisms, resistivity, mobility, stress induced leakage current, hot carrier injection, effective channel length and width are measured at room temperature by a SUSS PMF8 failure analysis 8" probe station connected to an Agilent 4284A LCR meter and to a Keithley 4200-SCS (Semiconductor Characterization System) configured with two remote PreAmps for low current measurements.

Scanning Tunneling Microscopy

The Laboratory hosts a Nanosurf easyScan2 STM (Scanning Tunneling Microscope). The easyScan2 STM is a modular scanning probe system. The main parts of the basic system are the scan head, the vibration isolation platform, the EasyScan2 controller.

STM scan head.

Maximum Scan Range: 500 nm

Maximum Z-Range: 200 nm

Current set point : 0.1-100 nA in 25 pA steps

Tip voltage: ± 10 V in 5mV steps

Tip sample approach: Stick-slip piezo motor

Sample size: max 10 mm diameter

STM allows the study of metallic nanoparticles on atomically flat surfaces (Highly oriented pyrolytic graphite (HOPG)). An accurately cut tip enables optimal measurements, achieving atomic resolution on HOPG surface. It is possible to perform experiments in the constant current mode (the tunnelling current is kept constant by the Z-controller, and the corresponding height is recorded as a function of X,Y), or in constant height mode (the tip does not follow the surface, but the variation of the tunnelling current is directly recorded as a function of the X,Y position.

Atomic Force Microscopy

The Atomic Force Microscopy laboratory is equipped with a Veeco diInnova Microscope. It offers a unique state of the art closed-loop scan linearization system that ensures accurate measurements and noise levels approaching those of open loop operation. The integrated, high-resolution color optics and programmable, motorized Z-stage make finding features and changing tips or samples fast and easy.

The top down optics of the Innova integrate seamlessly with all imaging modes, allowing for a direct view of the cantilever with better than 1 micron resolution, and ensuring precise probe positioning on the sample. With the optics positioned entirely inside the protective instrument cover, probe and sample can be viewed at any time while isolating the instrument from the environment. The ergonomic integration of the optics with the microscope also contributes to the ease and accuracy of tip exchange and laser alignment. The motorized, software controlled, optical zoom provides a broad range of magnification with an unparalleled resolution. With infinity corrected optics and illumination, the smallest sample feature can be located accurately.

INNOVA SPECIFICATIONS

 Closed-Loop Scanner: XY > 90 µm, Z > 7.5 µm

 Open-Loop Scanner: XY > 5 µm, Z > 1.5 µm

 Sample size: X-45 mm x Y-45 mm x Z-18 mm

 Motorized Z Axis Stage: Z Travel: 18mm

 Optics: Camera: on-axis color CCD with motorized zoom

 Field of view: 1.25mm - 0.25mm (motorized zoom, with 10x objective)

 Resolution: <2 µm with standard 10x objective (0.75 µm with 50X)

 Electronics: 20-bit DAC control, 100 kHz ±10v ADCs, digital feedback

 System software: SPMLa v7 for data acquisition & analysis

The Innova offers a full complement of SPM techniques, making it ideal for applications such as surface studies in materials science, characterization of polymers, biomolecules, and semiconductors, and nanomanipulation and nanolithography.

 

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