1. You are here:  
  2. Home
  3. Tempism
  4. Analysis
  5. Climatic Chamber
  6. Research
  7. Tempism
  8. Analysis

MBE1

Growth System MBE 1 (SiGe)

Paola De Padova  -

Carlo Ottaviani  -

Sandro Priori  -

Laboratory: IC11

Rome - Tor Vergata
 
 
The heart of an MBE apparatus resides into the Knudsen effusion cells (called K-cells or effusion cells) and in a system to monitor the epitaxy and/or film crystallinity. This is, for instance, the reflection high energy electron diffraction (RHEED) system. In this case the RIBER K-cells are designed for an operating temperature up to 1200°C, pyrolytic BN, or at 1400°C C-pyrolytic BN. Conventional temperature control based on the proportional–integral–derivative (PID) device join to a thermocouple feedback, provides a temperature stability ΔT of few °C
 
 

TECHNICAL SPECIFICATIONS

  • Working pressure ~10-11-11 mbar
     
  • Si(C-BN-1400 °C), Ge(BN-1200 °C, Mn(BN-1200 °C) K-cells; Si (flux=0.04 Å/min); Ge (flux=0.16 Å/min);
     
  • Sb, As, Bi- Surfactants effusion cells;
     
  • Ag, Au- Capping Layer effusion cells;
     
  • DC direct sample heating (RT-1200 °C) and Indirect heating (RT-450 °C ) systems;
     
  • Air-vacuum Fast Load-lock Sample Transfer System;
     
  • Variable e- HV (0-15 KeV) for RHEED system;
     
  • Hi-Speed Camera for real-time data diffraction acquisition (Image-software-MAC).

AVAILABLE TECHNIQUES

  • RHEED Ultra-High Vacuum (UHV) System for Surface Science Investigations; 
  • Cleaning Semiconductor (SC), Metal (M)-Surfaces reconstruction;
  • Epitaxial growth SC/SC, SC/Metal/SC;
  • Homo- and Hetero-structures growth: 1D, 2D and 3D Materials.
 

SAMPLES

  • Sample lateral dimensions: 10 x 5 mm (ideal), 3 x 3 mm (minimal), 10 x 10 mm (maximal);

  • Sample thickness: ideally up to 2 mm (thicker and/or smaller samples also feasible).
 

USED FOR

  • Fundamental Surface Science study;

  • Artificial Atomic Epitaxial Growth;;

  • Discovery of new 1D, 2D and 3D epitaxial   SC/SC; M/SC for micro-nanoelectronics and solar cells purposes;

  • Semiconductors for Microelectronics;

  • Microcircuits;

  • Ultra-thin Films;

  • Samples Cleaning;
     
  • Thin-film Stability;
     
  • Barrier Layers;
     
  • Lubrication;
     
  • Chemical Industry;
     
  • Coatings/Catalysis.
 
 

CASE STUDIES

Cross-sectional high-resolution transmission electron microscopy (HRTEM) image of a Mn0.06Ge0.94 film grown on a Ge(001)2✕1 substrate held at 520 K0.06Ge0.94 on Ge(001)2✕1

The structural, electronic, and magnetic properties of the Mn0.06Ge0.94 diluted magnetic semiconductor0.06Ge0.94, grown at 520 K by molecular-beam epitaxy on Ge(001)2✕1, have been investigated. Diluted and highly ordered alloys, containing Mn5Ge3 nanocrystals5Ge3. The valence band photoelectron spectrum of Mn0.06Ge0.94 shows a feature located at −4.2 eV below the Fermi level, which is the fingerprint of substitutional Mn atoms in the Ge matrix. Magnetization measurements show the presence of a paramagnetic component due to substitutional Mn atoms and of a ferromagnetic like component due to Mn5Ge3. The Mn L2,3 x-ray absorption spectrum of this polyphase film shows no marked multiplet structure, but a bandlike character.

See: P. De Padova, et al., Phys. Rev. B 77,  045203 (2008).

 
Immagine ad alta risoluzione in sezione-trasmessa ottenuta al microscopio elettronico a trasmissione (HRTEM) sul film di Mn0.06Ge0.94 cresciuto sul substrato di Ge(001)2✕1 tenuto ad una temperatura di 520 K.
 
 
Immagine ad alta risoluzione in sezione-trasmessa ottenuta al microscopio elettronico a trasmissione (HRTEM) di un film di Mn5Ge3 cresciuto sul substrato di Ge(111), misurata lungo la direzione di asse di zona [-1-12] del substrato di Ge(111). (b) Vista laterale a sfere e sticks di un'epitassia coerente tra il film di Mn5Ge3 e il substrato di Ge.
 

Spettri di assorbimento a raggi-X di L2,3 di Mn misurati per polarizzazione circolare della luce destra [σ+ (linea rossa)] and sinistra [σ− (blue dashed line)] e il corrispondente segnale XMCD (σ+ − σ−) (linea nera).

 

See: W. Ndiaye et al., Phys. Rev. B 91, 125118 (2015).

 

Mn5Ge3 film on Ge(111)

An investigation of the structural, magnetic and electronic properties of≈3 nm thick Mn5Ge3 grown on a Ge(111)-c(2✕8) reconstructed surface is reported. High resolution transmission electron microscopy and selected area electron diffraction give evidence of 2.2% in-plane compressive strain between the Mn5Ge3 and the Ge substrate. Magneto optical Kerr effect measurements show that the films are ferromagnetic with a Curie temperature of ≈325 K. The analysis of Ge 3d core level photoelectron spectra of the Mn5Ge3 allows determining an upper limit of 76 meV for the Ge 3d5/2 core-hole lifetime broadening Ge 3d5/2. The Ge 3d3/2 core-hole lifetime broadening is found to be 15 meV larger than that of the Ge 3d5/2 core hole3/2 5/2, because of the existence of a Coster–Kronig decay channel due to the metallic character of Mn55Ge3.

See: P. De Padova, et al., Phys. Rev. B 77,  045203 (2008).

 
 

XRD Seifert 3003

XRD Seifert 3003TT

XRD Seifert 3003P

Patrizia Imperatori  -

Laboratory RX

Rome - Monterotondo
 
The x-ray beam impinges the specimen under a specific angle Θ with the sample surface. The detector records the intensity of the beam reflected under the same angle Θ. Scanning the angle Θ one obtains a diffraction pattern. Strong reflected beams are detected when the path difference between reflections from parallel planes equals a whole number of wavelengths, according to the Bragg’s law:
                             nλ = 2 dsin Θ
where n is an integer (1, 2, 3, ...), λ is the wavelength   of the incident x-ray wave, d the lattice plane spacing andΘ the angle of incidence and reflection to the planes. Since every crystalline phase has a characteristic set of lattice spacings, the phases present in the specimen can be identified.
 

TECHNICAL SPCIFICATIONS

Seifert XRD 3003 TT

  • Two circle goniometer in symmetrical or asymmetrical Theta-Theta configuration. Angle scans are perfomed by X-ray source and detector (Theta-Theta scans), with the sample fixed in horizontal position. The reproducibility is ±0.0003°.
  • The diffractometer is equipped with a thin film attachment, consisting of long Soller slits and a flat graphite monochromator, for grazing incidence measurements.
  • NaI scintillation counter.
  • Cu Kα radiation (λ = 1.5418 Å)
Seifert XRD 3003P
  • Two circle goniometer in the Bragg-Brentano geometry, with a secondary curved graphite monochromator.
  • Cu-ka radiation (λ = 1.5418 Å) is employed..
  • Coupled or independent Omega/2Theta scans are possible.
  • A carousel with 12 sample-holders allows a sequence of measurements.
  • NaI scintillation counter.
  • Rayflex commercial software

AVAILABLE TECHNIQUES

  • Normal and grazing incidence X-ray diffraction from polycrystalline powders and films.
  • Qualitative and quantitative phase analysis.
  • Structural and microstructural analysis: lattice parameters, crystallite sizes, microstrain, texture.
  • Rietveld refinements.
  • ab-initio methods to solve structures.
 

SAMPLE

  • Crystalline powders and films

 

USE FOR

  • Metals

  • Semiconductors

  • Alloys

  • Catalysis

  • Pharmaceuticals

  • Cultural heritages

 
 

Case Studies

Nanocluster superstructures or nanoparticles?
The self-consuming scaffold decides

We show that using the same reaction procedure, by hindering or allowing the formation of a reaction intermediate, the Ag+dodecanethiolate polymeric complex, it is possible to selectively obtain Ag dodecanethiolate nanoparticles or Ag dodecanethiolate nanoclusters.
The XRD patterns of the nanoclusters present a sequence of equally spaced low angles peaks, which indicate the presence of a lamellar structure. The presence of low-angle peaks has been attributed to a cluster superlattice, whose d spacing is smaller than that of the corresponding pristine Ag+ thiolate complex, probably due to interdigitation.
The superstructure influences the chemical–physical properties such as luminescence in both the UV and NIR regions or the conductivity.

See: L. Suber, P. Imperatori et al., Nanoscale 10, 7472 (2018).

 
 
 
 

Tuning hard and soft magnetic FePt nanocomposites

Nanocomposites formed by hard and soft magnetic phases are very promising for magnetic energy storage and biomedical applications. Mainly depending on Fe:Pt atomic ratio, multi-phase or single phase FePt nanocomposites have been prepared by thermal treatment of core shell FePt(Ag)@Fe3O4 nanoparticles at 750°C for 1 h under flow of a Ar + 5% H2 gas mixture.2.
Performing Rietveld refinement of the XRD data the different phases have been singled out.
Besides single phase hard L10 FePt
and soft magnetic L12 2 Fe3Pt nanoparticles;
two phase soft α-FePt and ɣ-FePt
and hard and soft magnetic L10 FePt and soft L12 FePt3.
Nanocomposites have been formed and the structure and morphology correlated to their magnetic behavior.

See: L. Suber, P. Imperatori et al., J. Alloys Comp. 663, 601 (2016).

 
 

 

 

 

Scanning tunnelling microscopy (STM)

Scanning tunneling microscopy (STM) is a technique that allows the study of materials surface with a lateral resolution reaching the order of magnitude of a single atom. This extraordinary capability is obtained by scanning the sample surface by a metal tip maintained at a distance of a few nm, making possible a current flow by tunnel effect.
In addition to the microscopic investigation, scanning tunneling spectroscopy (STS) consents the study of the local surface density of electronic states.
The use of the tunnel microscope allows, therefore, a study of the structure of the surface and of the electronic properties of materials at the atomic level.

STM STM@ONSET

We use cookies essential for the functioning of the site. You can decide for yourself whether or not to allow cookies. Please note that if you refuse them, you may not be able to use all of the site's features.
Ok Decline
More information

ESCA-STM

ESCA-STM

Marco Di Giovannantonio  -

Nicola Zema  -

ONSET Lab

 

Rome - Tor Vergata
 
The ESCA-STM apparatus has been installed at the CNR-ISM in 2021 in virtue of the collaboration between Di Giovannantonio and the nanotech@surfaces laboratory of Empa (Switzerland). ESCA-STM is a combined photoemission/microscopy Omicron setup, designed for the study of surfaces and interfaces in ultrahigh vacuum (UHV) conditions. It consists of three UHV chambers – hosting a complete photoemission setup and a room temperature scanning tunneling microscope – plus a chamber for fast sample introduction in vacuum. Its special design allows coupling of additional experimental setups. ESCA-STM is employed to study on-surface chemical reactions toward the achievement of novel carbon-based nanomaterials for catalysis and organic electronics.
 

TECHNICAL SPECIFICATIONS

 Omicron system consisting of four main chambers

  • Fast-entry lock (FEL)
    • Sample introduction
    • 5 gas distribution lines
  • Transfer chamber
    • Sample exchange between FEL, PC and AC
       
  • Preparation chamber (PC)
    • Sample cleaning, preparation and inspection
    • Ion gun for sputtering (Ar+) with energy 0.8–5000 keV
    • 4-axis manipulator
    • Two heating stages: (i) resistive (RT–500 °C), (ii) e-beam (RT–900 °C)
    • Two ports for evaporators (CF40) with differential pumping
    • Quartz crystal microbalance (QCM) as thickness monitor
    • RT-STM
    • LEED
    • Quadrupole mass spectrometer (detection range 0–100 m/q)
       
  • Analysis chamber (AC)
    • X-ray source with twin anode (Al, Mg)
    • Monochromated X-ray source (Al)
    • UV source (HeI, HeII)
    • EA125 electron analyzer (5 channeltrons)
    • 5-axis manipulator with resistive heating stage and motorized azimuthal and polar angle movements

AVAILABLE TECHNIQUES

  • X-ray photoelectron spectroscopy (XPS), Twin anode + Monochromated X-rays
  • X-ray photoelectron diffraction (XPD)
  • UV photoelectron spectroscopy (UPS)
  • Angular-resolved photoelectron spectroscopy (ARPES)
  • Low-energy electron diffraction (LEED)
  • Room temperature scanning tunneling microscopy (RT-STM)
  • Mass spectrometry (MS)

 

SAMPLES

  • Samples are mounted on flag-style Omicron sample plates

  • Maximum allowed sample lateral size: 10 mm (diameter) or 8×8 mm2

  • Maximum allowed sample thickness: 3 mm

  • Sufficient conductivity to avoid charging during photoemission experiments and ensure stable tunneling current in STM

USED FOR

  • Metals

  • Semiconducting samples

  • Thin films

  • Single crystals and polycristals

 

TECHNIQUES AVAILABLE FOR PREPARATION/CLEANING

  • Ar+ ion sputtering with energy 0.8–5000 keV
  • Annealing (RT–900 °C)
  • Exfoliation of layered samples in vacuum
  • Evaporator for organics
  • Thickness monitor
 
 
 
 
 
 
 
 
 
 

CASE STUDIES

ARPES - Fermi surface maps

Our experimental setup allows the measurement of angle-resolved UPS data. Depending on the specific case, one can acquire full-3D ARPES plots (kx e ky vs E), carpet plots (kx vs E) o or angular maps (kx e ky) at fixed energy. We report here an example of the latter acquisition mode, where the Fermi surface of a clean Au(111) surface has been mapped using He I and He II as photon sources.
 

 
 
 
 
XPD plots
 
XPD angular plots display the angle-resolved photoelectron intensities from a particular emission line. At electron energies above ~500 eV, the scattering intensity is mostly directed in the forward direction, enhancing the photoelectron flux along the emitter–scatterer axis (forward-focusing effect). This method provides insights into the structure of surfaces and adsorbates. Here, we measured the XPD plot of a clean Au(111) sample at the Au 4f7/2core level, with both twin and monochromated X-ray sources.
 
 
 
 

Molecular self-assembly

One of the core activities carried out in our laboratory is the study of molecular systems on surfaces. The growth of covalent nanostructures can feature the appearance of intermediate phases. Here, we report the STM image of the Au(111) surface covered with a self-assembled phase of molecular dimers. The packing of the organic units into stable islands allows the identification of each molecule with high resolution. Image acquired at room temperature with an etched tungsten tip.

 
 
 
 
Work function determination
 
UPS measurements of samples that are biased allows the determination of the surface work function. Here, an ITO substrate was used to deposit a layer of MXenes. UPS measurements with the He I photon source of a 9 V biased sample revealed its work function of 4.32 eV.
 
 
 

Scanning Near-field Optical microscopy (SNOM)

The facility of Scanning Near-field Optical Microscopy (SNOM) allows to observe localized optical structures at the surface or in the bulk of any material. Images are obtained by illuminating the sample at a certain wavelength and measuring the local transmission or reflection of light together with topographic images. The comparison of simultaneously taken SNOM and topographic images allows to localize the optical structures in precise areas of the sample with nanometer resolution.

SNOM

We use cookies essential for the functioning of the site. You can decide for yourself whether or not to allow cookies. Please note that if you refuse them, you may not be able to use all of the site's features.
Ok Decline
More information
  English (UK)

Main Menu (en-GB)

We use cookies essential for the functioning of the site. You can decide for yourself whether or not to allow cookies. Please note that if you refuse them, you may not be able to use all of the site's features.
Ok Decline
More information