High-purity phosphorus (P2) source
Simple and safe operation with non-inflammable GaP source material
Compatible with most UHV and MBE systems
Various crucibles from 10 to 420 cm³
Precise and fast flux control with high reliability
Optional on-flange integrated cooling shroud and shutter
Adapted from WEZ and PEZ effusion cells, the simple construction of the DECO with its specially designed Ga-Trapping Cap Unit maintains the advantages of easy installation, full compatibility to all MBE systems, high reliability and low costs of ownership.
PBN Ga-Trapping Cap
on a DECO 40-10-22-KS
The DECO source features a unique Ga-Trapping Cap Unit system which provides a very pure P2 beam by decomposition of GaP. The idea underlying that unit is the sublimation of phosphorus from GaP at rather moderate temperatures at which gallium has only a low vapor pressure. By special baffle plates parasitic Ga atoms are efficiently separated from the P2 beam, thus producing a very pure P2 flux.
The Ga-Trapping Cap Unit is a simple but effective design consisting of only a small number of well-designed parts which are mounted onto the PBN crucible without additional tools or holders. For source maintenance and crucible refilling the unit is likewise easily removable.
Upon special request, a complete Ga-Trapping-Cap Unit is available as a product of its own, for retrofitting standard effusion cells.
Principle sketch of Ga-Trapping Cap Unit
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)]
It is also possible to use the DECO as an As2 or Sb2 source. The diagram below shows the analog curves for a Ga-As system. Please inquire for more information.
Equilibrium pressures of the components along the liquidus curve for
a Ga-As system
Typical applications of the DECO 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, the cell that is explicitly optimized for doping applications). All WEZ standard effusion cells are in principle also available with Ga-Trapping Cap Unit. DECO sources thus combine a most efficient, well-proven heating system with the unique principle of GaP decomposition, which leads to a very stable and reproducible P2 beam formation.
For growth applications the DECO is optimized toward a high flux rates, requiring relatively high operation temperatures and a large orifice of the cap. For these sources a maximum crucible volume is typically chosen to allow extended growth campaigns.
For phosphorus evaporation in large-scale and professional MBE systems, please see the Valved GaP Compound Source VGCS that offers larger capacities and even faster flux control.
Single crystal GaP source material with a purity >6N is offered together with the source.
There are several publications based on phosphorus growth with DECO sources.
|Filament type||Ta wire heating filament|
|Thermocouple||W5%Re/W26%Re (type C) (type K on request)|
|Operating temperature||900-1200°C for growth applications|
|Cooling||integrated water cooling or separate cooling shroud|
|Crucibles||10-420 cm³ PBN crucibles|
|Options||integrated water cooling (K), integrated rotary shutter (S)|
|Schematic drawing of the GaP Compound Source
For general information on CF mounting flanges see Flange and Gasket dimensions.
|[cm³]||[mm]||Type||[mm] / [mm]||[W] / [A]||Product code||Product code|
|DECO||40 -||10 -||22 -||S -||C -||P -||LxxxD34||120 / 6||PS 30-10||PBN 10-22|
|DECO||40 -||10 -||22 -||K||S -||C -||P -||LxxxD36||120 / 6||PS 30-10||PBN 10-22|
|DECO||40 -||35 -||34 -||S -||C -||P -||LxxxD35||180 / 7||PS 30-10||PBN 35-34|
|DECO||40 -||60 -||37 -||C -||P -||LxxxD38||520 / 13||PS 40-19||PBN 60-37|
|DECO||63 -||35 -||34 -||K||S -||C -||P -||LxxxD60||450 / 12||PS 40-19||PBN 35-34|
|DECO||63 -||125 -||54 -||S -||C -||P -||LxxxD55||800 / 14||PS 80-19||PBN 125-54|
|DECO||63 -||130 -||54 -||S -||C -||P -||LxxxD55||800 / 14||PS 80-19||PBN 130-54|
|DECO||63 -||200 -||58 -||C -||P -||LxxxD58||1280 / 16||PS 80-19||PBN 200-58|
|DECO||100 -||420 -||84 -||C -||P -||LxxxD84||800 / 12||PS 80-19||PBN 420-84|
|*||rotary shutter possible on same flange|
|***||specify UHV length L with order|
e.g. DECO 40-10-22-KS-C-L277D36
is a GaP compound source on DN40 CF-flange for a 10cm³ crucible (lip Ø 22), integrated water cooling shroud, shutter, type C thermocouple, in-vacuum length 277mm and diameter.