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Valved RF Crackers for Atomic Beam Epitaxy
with S, Se, Sb, Te, As, P
Most group V and VI elements evaporate as unreactive polymeric species. Thermal pre-dissociation at practical temperatures (<1500°C) results in reactive dimers, e.g: P2, As2, Te2. Dissociation to the most reactive atomic species, S, Sb, As, etc., can be achieved by passing the vapour through an intense plasma discharge.The very high reactivity of atomic species reduces feedstock inventory and chamber wastage. Additionally, the incorporation of a fast-acting valve, located at the cracker head, allows rapid control of the atomic flux over a wide dynamic range. The all-quartz RF valved crackers from Oxford Applied Research with patented , field-proven in-line control valve, integrated into our RF magnetic-multipole plasma source (500-plus in MBE systems worldwide), provide an advanced tool for MBE growers.
1. Calhoun, L.C. and Park, R.M. J.App. Phys. 85, pp 490, 1999
2. Doping of ZnSe
QC500

Specification

QC Series
High purity quartz (no metals)

Feedstock capacity

200/500cc
K-cell temperature

700oC (max)
Valve dynamic range

>100:1
Dissociation efficiency

 >90%
Beam diameter

23mm at source exit
Discharge chamber

high purity quartz
Flange mount

NW100CF
Bakeout (UHV compatible)

to 250oC
Options
Automatic tuning

Optical emission detector

Plasma controller

Servo-controlled valve

Full computer control






The graph below demonstrates sub-second manual flux changes. Note flux constancy and no overshoot

RF Solids Crackers - Application notes
Atomic Sb flux control (NAMBE paper)
Download brochure in PDF format: QC500