Surfaces and Interfaces

This research axis of the Materials-Nanosciences Department is interested in the growth and characterization of the electronic, optical and transport properties of heterostructures based on semiconductors, oxides, metallic and organic films

microscope à effet tunnel
  1. Application fields and studied heterostructures :
  2. Interfacial properties and technics
  3. Equipments :

Application fields and studied heterostructures :

The studied heterostructures mainly concern spintronics (spin valves or structures like metal/SC or metal/isulator/SC for the injection of spin polarised current into a semiconductor) and the grafting of semiconductor surfaces with functionalized organic monolayers. But we are also interested by structures for catalysis or components for nano and opto-electronics.
 

Application fields Studied heterostructures
Spintronic Schottky barrier : metal/SC :

Structures : metal/isulator/SC :

Spin valves :

Molecular functionalization of semiconductor surfaces
Catalysis
thin films growth or nano-objects
Components for the nano and opto-electronic
  • VCSEL Laser based on GaAs (*)

         (*) structures realized outside IPR  (collaborations).
 

Interfacial properties and technics

For each interface between two materials, we seek to describe the physicochemical properties (morphology, crystalline structure, reactivity) and the physical properties (electronic structure, transport, magnetism, optic). The table below specifies the technics used in each case.    
 

Properties Technics
Morphology scanning probe microscopies (STM, AFM), XPS
Crystalline structure Diffraction technics with electrons (RHEED, LEED), photoélectrons (XPD) and X-ray (XRD).
Reactivity XPS, XPD
Electronic structure XPS, UPS, STM/BEEM, PEELS
Electrical transport  I(V), C(V) measurements, local scale transport (STS/BEEM)
Magnetism Magneto-optic Kerr effect measurements (MOKE)
Optic microphotoluminescence and DOP

 

Equipments :

The structures are realised by epitaxial growth on monocrystalline wafers under ultra-high vacuum (UHV) by molecular beam epitaxy (MBE) or pulsed laser deposition (PLD). The growth chambers are coupled to the analysis chambers devoted to X-ray photoelectron spectroscopy (XPS) or scanning tunnelling microscopy (STM/BEEM). So we can follow in-situ and step by step the formation of interfaces. 

Equipment under ultra-high vacuum :

  • XPS analysis chamber (Mg/Al and monochromatic Al X-ray sources / HeI and HEII UV sources) coupled to a preparation chamber (heater, metallic and organic depositions).
  • XPS analysis chamber (Mg/Al X-ray sources / HeI and HEII UV sources) equipped with an angle resolved analyser (for X-ray photoelectron diffraction _XPD) and coupled to the epitaxial growth chambers (MBE for III-V semiconductors, metals and PLD for complex oxides).
  • STM analysis chamber working at room temperature modified into BEEM (Ballistic Electron Emission Microscopy) with magnetic field option and coupled to a preparation chamber (heater, metallic depositions).

Equipment at room atmosphere or controlled atmosphere :

  • Transport measurements  I(V), C(V), Hall effect, magneto-transport with low temperature option. Metallic contact on organic films with a mercury drop or by buffer layer assisted growth (BLAG).
  • Magneto-optic Kerr effect measurements
  • Degree of polarisation of photoluminescence (DOP).

Access to equipment outside the department

  • Atomic force microscopy (AFM) (IPR, Soft matter department)
  • Raman and microphotoluminescence  (SIR platform)
  • 4 circles Diffractometer for thin films (Institut des Sciences Chimiques de Rennes)