Diamond Foils

© Photo Fraunhofer CCD

Freestanding diamond foils find applications as windows for high-energy radiation windows. For example carbon foils interact with energetic ion beams by stripping of shell electrons without significantly slowing down the ions in accelerator physics experiments. Foils and windows differ in thickness, i.e. foils are several microns thic whereas windows can be as thick as a millimeter. The foils and windows are made from a range of diamond materials including nano- and microcrystalline doped and intrinsic variations. While being only a few microns thick the foils are mechanically rigid maintaining the pressure gradient from atmosphere to vacuum. Thus X-ray and electron beam sources operating in vacuum can use diamond foils as windows to direct the beams to the outside of the source.

Specifications

  • Flexible and stron freestanding diamond membranes
  • Various forms of diamond including nano-crystalline and micro-crystalline
  • Up to 10 microns thick
  • Several cm2 in size
  • Youngs modulus up to 1050GPa, depending on diamond material
  • Burst pressure up to 600kPa, depending on ratio of film thickness to lateral dimension and material
  • Mountable in frames

Fabrication

Films are initially deposited using microwave plasma assited chemical vapor deposition on silicon wafers as ultrananocrystalline, nanocrystalline or microcrystalline diamond by varying selected deposition parameters incuding gas composition, nucleation, power, substrate temperature and pressure. Subsequently the diamond is separated from the original susbtrate and applied either to new substrates or to frames. These substrates can be three-dimensional and the foils can be wrapped around them. The separation of deposition and application process proveides the opportunity to apply diamond thin films to substrate at room temperature.

Applications

  • Windows for X-ray source
  • Windows for radiation detectors
  • X-ray lithography membranes
  • Electron beam windows
  • Stripping foils for ion beam accelators
  • Diamond sheet protection of temperature sensitive materials