VGCS Effusion Cell  | © Scienta Omicron
VGCS. Source: MBE-K.

Valved GaP Compound Source (VGCS)

A High Purity P2-Source


  • 2 species (P2/P4 > 150)
  • Fast, stable and reproducible flux control
  • Large crucible capacity of 420 cm³>
  • Safe cell loading and operation
  • Reliable large cross section cone valve
  • No hot cracker zone
  • Injector length and flux distribution adjustable

The Valved GaP Compound Source (VGCS) is a high purity P2-source, based on the decomposition of high purity GaP. The concept is derived from the DECO effusion cell. A mechanical valve mechanism has been added for rapid beam flux control.

Full MBE compatibility is achieved by the integrated Gallium-Trapping-System, the integrated water cooling as well as the use of high purity inert materials such as pyrolytic boron nitride for all parts in the direct phosphorus path.

In contrast to sources using elemental phosphorus only minor amounts of white phosphorus are formed within the cell and the formation of white phosphorus within the MBE chamber is significantly reduced due to the direct formation of P2 species from the decomposition of single crystal GaP chunks with purity 6N-7N.

Operation of the mechanical valve unit shows fast, stable and reproducible flux control. Together with the valve controller an easy handling and integration to your MBE system is provided.

Further Details

  • DN100CF (6” OD) mounting flange
  • In-vacuum Diameter: 57 mm
  • Crucibles 420 cm³
  • Heating system with two separate heater-circuits for the cell and the valve
  • Two thermocouples Type C for the cell and the valve
  • Operating temperature of the cell crucible: 800-950 °C
  • Operating temperature of the valve: 350 °C
  • Outgassing temperature of the cell crucible: 1300 °C
  • Outgassing temperature of the crucible: 500 °C
  • Integrated water cooling shroud
  • Bakeout temperature up to 300 °C
  • Flux control with integrated valve unit
  • Valve control either via hand control or by a motor drive with a control unit


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