Valved Cracker source for Phosphorus :
KPC SERIES
n Full modularity of the design for simple P charge n loading, maintenance or further upgrading n ...
n Full modularity of the design for simple P charge n loading, maintenance or further upgrading n “Zero burst” patented design n Three-zone temperature concept n Fast and precise control over phosphorus flux n 100% leak tight all metal metering valve n Wide product range from 250cc to 2500 cc n Low condenser temperature to avoid Pwhite n instabilities
KPC250
The RIBER multi-zone phosphorus valved cracker source is
The source-zone is connected to a valve that provides me-
dedicated to III-V base semiconductor MBE growth, desi-
chanical means of instantaneously controlling the tetramic
gned to procure loading capacity, beam flux levels, rapid
phosphorus vapor flux over several decades, while offering
flux adjustment/shut-off possibilities and cracking efficiency
complete chamber isolation if reloading the source is requi-
that meets the requirements of the production environ-
red.
ment.
A cracker zone situated at the outlet of the source brings
The cell consists of three main assemblies made of carefully
thermal means to crack the primary vapor to P2 molecules
selected materials which are chemically and heat-treated
independently of the flux level, thus ensuring minimum di-
to provide state of the art flux purity.
rect white phosphorus formation inside the growth chamber
A vapor generator source-zone produces a stable vapor
and bringing an additional level of process control.
of tetrameric molecules through in-situ sequential or simul-
The instrument is fully modular; any of the main assembly
taneous conversion to white phosphorus of part of the red
can be serviced or replaced independently of the others as
phosphorus charge.
simply as disconnecting a Conflat® flange.
W ORK I N G P R I N C I P LES The evaporator is placed inside the condenser and receives the
justment and complete interruption of the phosphorus flux in the
red phosphorus primary loaded charge. For an easy loading, the
cracker. The valve is fully leak tight in the closed position enabling
evaporator heated crucible is mounted on an independent base
cell reloading without venting. The valve is externally heated by a
flange. After loading, the red phosphorus is heated to an evapo-
heated mantle to prevent white phosphorus condensation on the
ration temperature to produce P4 that will condense into white
valve mechanism.
phosphorus. The condenser surrounds the red phosphorus and is connected to the flux valve. An isolation valve vents and pumps
The cracker stage is inserted inside the growth chamber and is
down the condenser during re-loading operations. P4 vapor
connected to the valve.
condenses on white phosphorus and the condenser wall and is re-evaporated at a rate dependant upon the condenser tempe-
A high conductance transit tube allows the transfer of P4 mole-
rature typically 60/100°C.
cules to the cracking zone. The cracker stage design allows an efficient dissociation of the P4 molecules into the cracking zone.
The condenser is set in a thermostatic enclosure allowing inde-
The cracker stage design allows an efficient association of the P4
pendent temperature control of the condenser between 40 and
molecules to dimmers. The cracker is heated by a flat Ta filament.
120°C.
A wire thermocouple is used to monitor the cracker stage tempe-
The enclosure is heated with a fan assisted force air circulation and
rature.
temperature is monitored by a controller. An independent and optional water panel can be provided around An all-metal valve is placed between the condenser and the
the cracker to limit the heat load in the growth chamber.
cracker stage. It is fully independent and can easily be serviced or replaced. The micrometer driving mechanism enables fine ad-
Evaporation (T ≈ 300 - 350°C)
P red
Evaporator
Condensation (T 850°C)
P4
Cracking zone
s p e ci f ic a ti o n s requirements A valve controller is strongly recommended
Schematic view of the KPC1200
for KPC250 and KPC1200
Evaporator loading flange
Multi-valve controller
Thermal enclosure
NVC6000
Condenser
Cracker power & T/C feedthrough Valve heating mantel Single-valve controller
