-A A +A

 

The characterization laboratory of IMM-NA offers equipments and expertise devoting to the investigation of materials and devices. A variety of characterization techniques are made available in the following fields:

  1. Microscopy and imaging,
  2. Electrical characterization
  3. Optical characterization.

*************************************************************************************************

1. Microscopy and imaging

Includes three areas: electron, scanning probe and optical.

Scanning Electron Microscope (SEM); For elemental and structural characterization of samples,  a field emission scanning electron microscope (Carl Zeiss NTS GmbH 1500 Raith FESEM) is used. The SEM is equipped with secondary emission and in-lens detectors. Accelerating voltage is up to 30kV and apertures are 7, 10, 20 and 30µm wide. This SEM is integrated in a Raith 150 Electron Beam Lithography System, placed in a laboratory, that is a ISO 5 clean room located in Research Area Naples 3, Via Campi Flegrei 34, 80078, Pozzuoli (Na).

People: Emanuela Esposito, Alessio Crescitelli, Valentina Di Meo, Pia Dardano

 

Scanning probe microscopy:  is an imaging tool with a vast dynamic range, spanning the realms of optical and electron microscopes.

Atomic Force Microscope (AFM) provides 3 dimensional topographic information about a sample by probing its surface structure with a very sharp tip. Our AFM is a XE-70 microscope from Park Systems. The instrument is provided with two independent, closed-loop XY and Z flexure scanners for sample and tip, respectively. Flat and linear XY scan of up to 100 μm x 100 μm with low residual bow is provided.
Out of plane motion is less than 2 nm over entire scan range. Z-scan is up to 25 μm by high force scanner. Non-contact mode and contact mode are used to characterize nanostructured materials and biomaterials. In the case of biomaterials, sample preparation protocol has been developed. Moreover, Force spectroscopy is available to study mechanical interactions as morphological deformation in soft-matter. Force-Distance (F-d) curves is a spectroscopy technique measuring the vertical interaction between the tip and the sample surface while extending and retracting a Z scanner. Function of a cantilever deflection versus the extension of the piezoelectric scanner is direct measurement of tip-sample interaction forces reflecting a mechanical property of surface.

People:  Giuseppe Coppola, Maria Antonietta Ferrara, Principia Dardano, Ilaria Rea, Shomnath Bhowmick.

 

Electrostatic Force Microscope (EFM); The EFM uses the XE-70 microscope combined with the Lock-in Amplifier SR-830 both from Park Systems. Generally, the standard EFM scans twice in each force dominant regime to distinguish electric force and Van derWaals force effect. In this way, it is possible to map a localized charge distribution on an insulator layer, the ferroelectric domain, the local surface potential distribution or variations in surface work function. Enhanced EFM applies AC bias (frequency ) to tip and gets  signal using the Lock-in Amplifier to distinguish electric force and Van derWaals force effect.

People: Principia Dardano, Shomnath Bhowmick.

 

Optical microscopes; The Lab has two standard microscopes utilised for materials preparation and/or device analysis and two optical microscope realized in lab: holographic microscope and coherent Raman microscope.

Holographic microscope: enables the reconstruction of both the amplitude and the phase maps of the object to characterize. In particular, the phase map enables a three-dimensional reconstruction of the object. Such a microscope is equipped with a coherent laser source with a coherence length> 100m.

People: Giuseppe Coppola, Maria Antonietta Ferrara, Gaetano Bianco, Valerio Striano (CGS).

 

Coherent Raman Microscopy: Stimulated Raman Scattering (SRS) microscopy is sensitive to the same molecular vibrations probed in spontaneous Raman spectroscopy, but unlike linear Raman spectroscopy, SRS technique exhibit a nonlinear dependence on the incoming light fields and produce coherent radiation. Therefore, SRS microscopy makes possible to achieve images faster than conventional Raman microscopes. In our laboratories, a prototype of SRS microscope which uses femtoseconds laser sources was successfully implemented. The laser sources are: Ti:Sa Chameleon Ultra-II with ultrashort pulses (140 fs @ 800 nm), high repetition frequency (80MHz), tunable in wavelength in the range 680-1080 nm and peak power >3.5W.   Chameleon Compact OPO tunable in wavelength in the range 1000-1600 nm and average power> 700 mW at 1000nm. The Ti:Sa and OPO beams were collinearly combined temporally overlapped and focused inside the sample by a 60X high numerical aperture multiphoton objective. Output pulses are collected by a 40X high numerical aperture multiphoton objective (Nikon, Apo 40X, NA 1.25). Afterwards, a stack of optical filter removes the pump pulses, while probe pulses are detected by a PD. The filtered current is measured by a high frequency LIA. SRS spectroscopy set up is integrated in an inverted research microscope (Eclipse TE-2000-E, Nikon) equipped with a fast mirror scanning unit (C2, Nikon). Theexcitation beams, overlapped in time and space, are directed into the microscope through the mirror scanning unit. After interaction with the sample, the beams are collected by a forward detector inserted in the inverted microscope. 2D image is obtained by synchronizing our forward detection unit with the microscope scanning unit. The synchronization is achieved by managing by PCI card (NI PCIe 6363), the electrical signal from the LIA and the digital signals from microscope scanning unit controller. It is worth noting that nonlinear microscopies based on SRS are not purchasable. They can be realized only in research lab.  In the world there are a number of nonlinear microscopies based on vibrational spectroscopy, but the most of them are based on CARS and a few on SRS. In Italy, at this time, there is only another group working on the realization of a similar microscope. The most of SRS applications are aimed at label-free imaging of lipids in a variety of samples from artificial model systems, to living cells and tissues. This prevalence is due to the important role of lipids in biology and to favorable signal strengths in CRS experiments. CRS microscopy can help to solve many open questions on lipid-related processes inside cells and tissues, which due to the limitations and artifacts associated with fluorescence lipid staining have been left open.

People: Luigi Sirleto, Annalisa D’arco, Maria Antonietta Ferrara, Maurizio Indolfi, Vitaliano Tufano.

 

A new encoding techniques in imanging with structured light and single pixel detection: Color-encoding of phase for incoherent complex fields; Digital Micromirror Device (DMD) for light modulation at high refreshing rates (up to 30 kHz). Digital Light Projector (DLP) equipped with three leds (red, green and blue) and hosting the DMD. Custom codes for the reconstruction of images starting from single-pixel signals.

People: Edoardo De Tommasi, Michael Mazilu (University of St. Andrews, Scotland, UK)

 

*************************************************************************************************

2. Electrical characterization: 

Charcterization of materials and devices are performed by the four-point and two-points measurement technique, respectively.

*************************************************************************************************

3. Optical characterizations: 

The Lab has some standard instrumentations and in addition a number of experimental set up implemented.

Spectroscopic Ellipsometer Horiba UVISEL NIR: spectral range 245 - 2100 nm, automatic goniometer automatically adjustable angle from 40° to 90° by step of 0.01°. It is based on phase modulation technology, providing high accuracy and high resolution measurements with an excellent signal to noise ratio. It is a standard instrument, although with unique and innovative features. Most of the originality can be found in the data elaboration software, which allows to model a huge variety of simplex and complex materials and structures.

People: Mario Iodice

 

Infrared spectrometry: is useful for the identification of both organic and inorganic compounds. Infrared spectrometry is ideal for the identification of functional groups present within a sample. Instrumentation: FT-IR Thermo-Nicolet Nexus spectrometer

People: Ilara Rea

 

Optical Characterizarion of materials and devices by a supercontinuum laser. The optical laboratory is equipped with a supercontinuum laser (SuperK Extreme NKT Photonics), which allows a high output power, a broad spectrum, and a high degree of spatial coherence. The emission spectrum is 400-2400 nm and, by using the Acousto-Optic Tunable Filters, the SuperK can be converted into an ultra-tunable laser up to 8 simultaneous lines. It is possible to use this light source to characterize dielectric or metallic nanostructures, such as photonic crystal structures or gratings. In addition the system can be used for low-coherence "white light" interferometry, for the spectroscopy of biological, chemical or medical samples or for photonic devices testing, such as fiber and waveguide attenuation measurements.

People: Silvia Romano, Vito Mocella

 

Optical characterization of devices: Homodyne technique measurement is employed in order to precisely extract the output current emitted by a detector in an extremely noisy environment. The experimental set-up is based on the use of a near-infrared tunable laser (ANDO AQ4321D), a trans-impedence amplifier (Melles Griot 13AMP005) and a lock-in amplifier (Signal Recovery 7280DSP). In addition, the bandwidth detector is characterized in time domain taking advantage of both a femtosecond pulsed laser (Ti:Sa Chameleon Ultra-II and Chameleon Compact OPO) and a high-speed oscilloscope.

People: Maurizio Casalino, Giuseppe Coppola, Mario Iodice, Luigi Sirleto

 

Source: 
News: 
Research Topic Term: