Download a short descrition of INS (in french, extracted from Annual Report 2013)

 

General presentation of the INS station

The INS station is the third and last experimental station. It is devoted to studies of surfaces, interfaces and thin films in Ultra High Vacuum, by means of three techniques using hard X-rays: Grazing Incidence X-ray Scattering (GIXS), Surface Extended X-ray Absorption Spectroscopy (SEXAFS, ReflEXAFS) and X-ray Reflectivity. It is made of a large and well-equipped UHV chamber mounted on a 4-circle diffractometer for X-ray studies, coupled to several other UHV chambers located outside the X-ray hutch, which have been added by the local team, and are thus not opened to external users unless a strong collaboration is initiated.

The diffractometer supports the UHV chamber, with allowance for a rotation of the whole chamber defining the incidence angle (a) of the X-ray beam with respect to the vertical sample surface. A goniometric head allows alignment (two perpendicular tilts (c1 and c2), two translations (X, Z)) of the sample inside vacuum. The rotary motion of the sample is obtained through the rotation of the whole goniometric head thanks to a differentially pumped rotary feedthrough (w). Two sample surface orientations (parallel and perpendicular) with respect to the X-ray beam polarization are possible. Two circles of the diffractometer are devoted to the two detector rotations defining the Bragg angle projections parallel and perpendicular to the surface (d and b respectively). The x-ray UHV chamber has large Be windows giving access to large perpendicular momentum transfers (up to 45° input and exit angles). It is equipped with several sources (up to six simultaneously) for in situ epitaxial deposition and with standard UHV preparation and analysis tools (high temperature furnace, Reflection High Energy Electron Diffraction (RHEED), Auger Electron Spectroscopy (AES), Residual Gas Analysis (RGA), Ion Sputtering (IS), quartz micro-balance for calibration of deposition). Simultaneous real-time analysis with x-ray diffraction and RHEED and Auger spectroscopy can be performed during (co)deposition and/or annealing of ultra-thin films.

Photograph of the X-ray station of the SUV setup

Photograph of the X-ray station of the INS setup. The beam comes in through a small Be window (the right hand side) and exits through a large Be exit window.

 

Main characteristics of the motions

  Goniometer   Sample holder
Circle a
(deg)
b rot
(deg)
b trans
(mm)
d
(deg)
w
(deg)
Height
(mm)
c1
(deg)
c2
(deg)
X
(mm)
Z
(mm)
Mechanical resolution
(per motor step)
0.0005 0.0005 0.005 0.001 0.0005 0.0005        
Range 0-40 0-40 0-500 0-135 ±200 0-50 ±4 ±4 ±5 ±5
Precision <0.01 <0.01   <0.01 <0.01          
Concentricity (µm) ~30     ~30 ~20          
Repeatability £0.005 £0.001   £0.01 £0.005   0.01 0.01 0.005 0.005

 

Other equipment

INS is not only limited to the x-ray station. It is a large experimental set-up, schematically shown in the Figure, which has been continuously upgraded and improved by a CNRS/Cristallography and CEA/SP2M laboratory staff. The non x-ray equipments are : a complete MBE system devoted to nitride and Si/Ge growth, and a characterisation chamber equipped with quantitative LEED and Auger analysis, both connected in UHV via a large transfer system crossing the lead wall of the x-ray hutch. The MBE chamber was the first to be connected to the X-ray station. For samples which could not be produced in the X-ray chamber, the transfer system has been used successfully and some experiments were already carried out.

Schematic drawing of the complete SUV setup.

Schematic drawing of the complete SUV setup.

 

Specific properties

Specific properties when compared to other surface diffraction stations at ESRF:

  • The shared beam time with the other station makes it possible to investigate systems that require significant preparation before performing an X-ray experiment ( the UHV and the MBE chamber can be available before an experiment).
  • RHEED, SEXAFS and GIXS experiments on the same sample.
  • Co-deposition: deposition of up to 6 materials.
  • Better signal to noise performances for samples with large mosaic spreads (~0.1°) because of the large horizontal beam divergence.
  • Fast sample introduction system.
  • High temperature furnace (up to 1000°C). The temperature of the furnace can be controlled by a computer interface.
  • Sample cooling down to -100°C, optional.
  • The beam energy can be changed easily and continuously.
  • Horizontal and vertical sample geometry exchangeable in ultra-high vacuum allowing for polarisation analysis with SEXAFS on the same sample.
  • For diffraction experiments needing high precision, a second goniometric sample holder, simpler than the previous one and for vertical sample geometry only, will soon been available.
  • The transfer system makes it possible to produce samples in other chambers or to characterise the same sample with complementary techniques in the different chambers.

 

Examples of SUV Experiments