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DECO 40-60-37 GaP Compound Source for Phosphorus (P2) , on a flange DN40 CF (O.D. 2.75"), with 60 cm³ PBN crucible and Ga-trapping PBN cap

 
  • Ultra high purity Phosphorus (P2) source
  • Compatible with most MBE systems
  • Effusion cell-like operation
  • Safe and pure doping or growth techniques
  • Various crucibles, capacity 10-200 cm³
  • Simple construction, low cost, high reliability
  • Precise and fast flux control
  • Optional: on cell flange integrated cooling shroud and shutter

  GaP Compound Source DECO Data Sheet ( 442 kB pdf-file )

  
 
 
 

The Compound Source DECO is an ultra pure source for P2 based on the decomposition of GaP. It is a reasonably priced and easy to operate alternative to valved phosphorus sources, like our VGCS.

The simple construction of the DECO, based on our WEZ and PEZ cells, and the specially designed Ga-Trapping-Cap System have the advantages of easy mounting, full compatibility to all MBE systems, high reliability and low cost. The operation of the DECO is comparable to usual effusion cells and does not require complicated mechanical valves and controllers. Compared to the operation of an often used valved cracker the deposition of white phosphorus (P4) within the growth chamber is significantly reduced due to the direct generation of pure P2.

MBE-Komponenten GmbH has developed special sources based on the Ga-Trapping-Cap System (see below). We build the DECO optimized for growth applications with high evaporation rates and large crucible capacities.
Alternatively an optimized version for special doping applications (type DECO-D) is available, e.g. as phosphorus doping cell for Si MBE with a reduced cell shutdown time.

The heater of the DECO is designed very similarly to the WEZ-heater which consists of a Ta wire filament supported by PBN rings. Crucible material is PBN. With this design minimum outgassing at operation temperature is achieved, in combination with excellent reliability, long-term stability and extended lifetime.

Excellent operation temperature stability of ±0.1°K is achieved by an improved design of the thermocouple assembly. This assembly touches the crucible near the base. The direct touch technique and the use of double pairs of TC-alloy wires ensure a reproducible and stable measurement of the real crucible temperature.

  

Ga-Trapping PBN cap on a DECO 63-125-54


  
 

Ga-Trapping-Cap-System

MBE-Komponenten produces a unique system which provides a very pure P2 beam by the decomposition of GaP. The Ga-Trapping-Unit, consisting of a few well designed parts, can be easily mounted on a standard effusion cell. The Ga-Trapping-Cap System is based on the sublimation of phosphorus from GaP. The parasitic Ga atoms are efficiently separated from the P2 beam. Thus a very pure P2 beam is produced.

The Ga-Trapping-Unit can be mounted on standard effusion cells without additional tools and materials, it also can be easily removed to change or refill the crucible.
In addition to the complete DECO we offer the Ga-Trapping-Unit as a product of its own. Please contact us for further information.

   
 

Equilibrium pressures of the components along the metal-rich boundary of the field of solidus of a Ga-P system [R.F.C. Farrow, J.Phys. D, 7, 2436 (1974)]

  

  • high operating temperatures 900-1200°C for growth applications
  • very good temperature and flux control
  • fast switch of flux
  • very stable and reproducible flux
  • precise P2 control in GaAsP, GaInAsP etc. compounds
  • P2/P4 ratio about 150
  • very low parasitic Ga flux (P : Ga > 103)
  • high efficiency: about 10 g P in GaP for
    100 µm film thickness
  • scarcely any white P accumulation in MBE system
  • no additional safety facilities needed in contrast to PH3, AsH3 or valved elemental Phosporus crackers
  • no bakeout necessary before opening the system
  • compatible with standart III/V solidsource MBE
  • requires no additional pump
  • simple but effective design
 
 


Application

Typical applications of our DECO compound sources based on the Ga-Trapping-Cap System are the growth of phosphide compounds (GaInP, InP) in III-V MBE as well as Phosphorus n-type doping in Si MBE (with DECO-D). MBE-Komponenten provides well designed standard effusion cells with the Ga-Trapping-Cap System. This GaP compound source DECO combines our most efficient heating system, known from our WEZ cells with the Ga-Trapping-Cap System. Thus a very stable and reproducible P2 beam is achieved.
For growth applications the DECO is optimised towards a high flux which requires high operation temperatures and maximized openings of the cap system. The cell is also optimized to maximum crucible volume to allow long time operation. Single crystal GaP material with a purity >6N is recommended as source material. A valved GaP compound source (VGCS) with larger capacities is available, too.

It is also possible to use the Ga-Trapping-Unit and the DECO as an As2 or Sb2 source. Please ask for more information.

(See References for DECO)

      
 

Technical Data

Filament type Ta wire heating filament, optimized for growth application
Thermocouple W5%Re/W26%Re (type C); (type K on request)
Bakeout temperature 300°C
Operating temperature 900-1200°C for growth applications
Outgassing temperature 1500°C
Cooling integrated water cooling or separate cooling shroud
Crucibles 10-200 cm³ PBN crucibles
Options integrated water cooling shroud (K), integrated shutter (S)
  
 
 

Dimensions

Schematic drawing of the GaP Compound Source DECO 40-35-34-S

 
 
 

Specific Data

For general information on CF mounting flanges see "Flange and Gasket Dimensions".

System manufacturer:    MBE-Komponenten, Omicron and other manufactures not separately listed
 
      [cm³] [mm]     Type [mm] / [mm]   [W] / [A] Product Code Product Code
DECO 40 - 10 - 22 -   S* - C - LxxxD34   120 / 6 PS 30-10-C PBN 10-22
DECO 40 - 10 - 22 - K S* - C - LxxxD36   120 / 6 PS 30-10-C PBN 10-22
DECO 40 - 35 - 34 -   S* - C - LxxxD35   180 / 7 PS 30-10-C PBN 35-34
DECO 40 - 60 - 37 -     C - LxxxD38   240 / 8 PS 30-10-C PBN 60-37
DECO 63 - 35 - 34 - K S* - C - LxxxD60   240 / 8 PS 30-10-C PBN 35-34
DECO 63 - 125 - 54 -   S* - C - LxxxD55   280 / 9 PS 30-10-C PBN 125-54
DECO 63 - 200 - 58 -     C - LxxxD58   320 / 9 PS 35-20-C PBN 200-58
*    rotary shutter possible on same flange             
**  PBN as standard, other materials on request      
*** specify UHV length L with order      


Example for Product Identfication Code:

DECO 40-10-22-KS-C-L277D36 is a GaP compound source on DN40 CF flange with 10cm³ PBN crucible, integrated water cooling shroud, shutter, type C thermocouple and UHV-length 277mm.
 
 
 

 LAST UPDATE: MAY, 2006

© 2003 Dr. Eberl MBE-Komponenten GmbH