A low cost and easy alternative to the cracker source
Uses GaP (or GaAs) loading material (P2 / Ga @ 103)
As easy to operate as a standard group III cell.
Available in models adapted for all types of R & D or production reactors
Fig.1:This curve gives the Phosphorus dimere BEP values versus the compound source temperature. (Source baffle extremity to substrate distance is 120 mm)
set ramp
measered flux
P2 flux modulation driven by a standard PID controller in ramping mode.
SIMPLE PHOSPHORUS P2 BEAM CELL FOR SOLID SOURCE MBE This cell produces a pure P2 beam from the evaporation of GaP material. The separation between P2 and Ga is made within a special Trapping Baffle Unit placed at the mouth of the GaP cell crucible. The ratio between P2 and P4 is higher than 150 when P is produced by GaP effusion. Thus very little Pwhite deposition on to the system wall is observed with this type of cell. The low vapor pressure of P2 over GaP allows work at medium/high cell temperatures. This gives precise, stable and reproducible flux adjustments and avoids loss of GaP charge during bakeout of the system. Demonstrated results (red laser structures, pseudomorphic InGaP/InGaAs/GaAs HEMT...) show that this type of cell gives P2 beams with better purity and cleanliness than other more sophisticated methods.
BENEFITS:
Ease of use and installation.
Full compatibility with the standard ion pumping.
Stable and reproducible flux.
High P4 rejection ratio. ( P2/P4 is about 2.102. Equivalent to a cracking efficiency higher than 99,5%)
High Ga rejection ratio (Ga/P is about 10-3 )
Virtually no Pwhite accumulation. No loss of source material during bakeout of the system.
High material efficiency: 1g of Phosphorus for 10µm of film.
OPERATING PRINCIPLE: The cell crucible is loaded with the compound material. The evaporated species (Ga and P2) flow through PBN cold baffles in which the Ga portion recrystallizes into GaP leaving the Phosphorus in excess. The majority of the P molecules then exits through the baffle aperture. This process is very efficient and only a very weak
Ga parasite component is found in the final beam. Parasitic Ga fluxes lower than 2 x 10-11 Atoms/cm2 are generally reported for P2 BEP fluxes in the 10-6 Torr range
( 0.3 to 1 µm/h of GaInP).
BEP and load efficiency. Reported temperatures/ P2 BEP are shown in figure 1. An average total thickness of 90 µm of InGaP layer growth is reported for a 55 g of poly GaP load corresponding to the 35cc compound cell model.
Models Models may be adapted for each system including home-made or specially designed ones.
They are all compatible with existing power-supplies and electrical connections.
All compound cells have cell body Integrated Water Cooling (W)
V80
DN63CF
4" (114 mm)
85
GAP85VG8W
863085
V90
DN63CF
4" (114 mm)
85
GAP85VG9W
863085
V100
DN100CF
6" (152 mm)
500
GAP500VG1W
800500
Varian / Intervac
Gen II
DN40CF
2,75" (70mm)
35
GAP35VA2
835035
Mod Gen II
DN63CF
4" (114 mm)
85
GAP85VA3
863085
Others
and manufacturers not listed above Integrated Water Cooling is a factory option*
Flange Size
DN40CF
2,75" (70 mm) or higher
35
GAP35AD1
835035
Flange Size
DN63CF
4" (114 mm)
or higher
85
GAP85AD2
863085
Flange Size
DN100CF
6" (152 mm)
or higher
500
GAP500AD3
800500
* When needed Integrated Water Cooling can be added as a factory option (W).
Do not hesitate to contact ADDON if your system is not listed above or if your system is a custom designed one.
