Standard Temperature Effusion Cell

The Standard Temperature Effusion Cell (STEC) is used to deposit a wide range of materials with a moderate vapour pressure (e.g. Ga, Al, Si, Cu …) for molecular beam epitaxy (MBE). The STEC features a patented flat foil Tantalum filament that minimizes the temperature difference between the crucible and the filament. The filament design has many benefits: 

• Better thermal load distribution. 

• Rigid design, deformation limited. 

• No magnetic field due to the opposing coils compensating each other. 

• The top connecting ring can be designed so that the crucible orifice may be hotter than the crucible body, improving beam quality. 

Available crucible capacities are 6 cc, 13 cc, 20 cc, 23 cc, 40 cc, 60 cc, 100 cc, 150 cc and 200 cc. Both conical and bottle neck crucible designs are available. For bigger crucible volumes of 500 cc, 1000 cc and 2000 cc, the used filament is either pBN-coated PG or Ta-wire. 

A single filament STEC, or STEC-SF, is suitable for depositing e.g. aluminum or doping Si and Be. When delivered from DCA, the aluminum STEC-SF considers the special requirements of the Al. It keeps the crucible lip cold to prevent creeping, heats slowly near the melting point and keeps the Al molten during error conditions. 

A dual filament STEC, or STEC-DF, features two independent heating filaments split between the upper and lower crucible sections. Adjusting the top filament prevents material condensation on the crucible orifice, while maintaining optimal evaporation with the main filament. It is the most suitable for growing very low defect density films of gallium or indium.