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Department of Physics

The Cavendish Laboratory

Molecular Beam EpitaxyMBE is an ultra high vacuum technique for the epitaxial (layer by layer) deposition of thin films. We use this technique for the growth of very high purity III-V semiconductors where the thickness of layers can be controlled with sub monolayer precision.

There are four MBE systems currently in operation:

  • A VG V80H growth chamber, known as the 'A' chamber, which has been in operation since 1986 and which has grown around 4000 wafers in the InGaAs/AlGaAs/GaAs material system. This chamber is attached to a surface decontamination chamber and a focused ion beam system, both of which have been used for the fabrication of 3D semiconductor structures.
  • A Varian Gen II system, formerly at the Philips Research centre in Redhill, was installed at the Cavendish in 1991. This machine has been used for the growth of very high mobility 2D electron and hole gases in the GaAs/AlGaAs system.
  • A Veeco mod GEN II system, installed in 2002, which is capable of uniform growth on 3 inch substrates, is used mainly for the growth of THz quantum cascade lasers as well as samples in the GaInAs/AlInAs/InP system.
  • A Veeco GEN III system, installed in 2007, will take over much of the InGaAs/AlGaAs/GaAs work from the 'A' chamber. This system, which has 12 source ports, is capable of highly uniform growth over 3 inch substrates and is connected to a surface decontamination chamber for regrowth on patterned substrates.

Aluminium effusion cell for GEN II systemAs well as being used in many projects at the Cavendish, samples from these systems are used by around 15 other universities and three industrial organizations.