- Compatible with all MBE systems
- Conical shaped crucibles with crucible capacities 2, 5, and 12 cm³
- Most effective Ta-wire heating system
- Large flux distribution providing excellent homogeneities
- High reliability and long lifetime
- Optional: on cell flange integrated shutter
Introduction
Our effusion cells WEZ and NTEZ are generally designed for elemental and compound evaporation or sublimation in the temperature range from 200°C to 1400°C.
Doping applications in MBE growth however require only low quantities of dopant material. Therefore, compact effusion cells with small crucible capacities and low flux rates, but wide angled flux distribution are needed. A typical doping flux is about 3 to 5 orders of magnitude smaller than a typical growth material flux. The Doping Effusion Cells DEZ with conical crucibles provide low power consumption, while producing excellent doping uniformities. For example, a doping level uniformity of about 1% on a 3" substrate at a distance of 150mm is reached with crucibles having a tapering angle of 10%. DEZ cells can be used as doping source for various materials like e.g. Si, Be, Ga or In.
To facilitate the source selection by doping application we have created a special Doping Application Guide, where we compiled source recommendations for the most common doping applications.
Beside the standard crucible material PBN (pyrolytic boron nitride), other crucible materials such as Al 2 O 3 or PG (pyrolytic graphite) are also available. The crucible is heated by a tantalum wire filament supported by PBN rings. This wire heater concept provides excellent temperature uniformity within the crucible and effective heating even at the crucible lip, and allows the use of different shaped crucibles. Due to the reduced touch between the filament wires and the PBN supporting rings minimum decomposition of PBN at operation temperature is achieved. Other advantages are excellent reliability, long-term stability and an extended lifetime, compared with Ta-foil heaters.
Application
The Doping Effusion Cells DEZ are recommended for elements and compounds evaporated or sublimated at temperatures in the range 200-1400°C, e.g. Ga, In, Al, Si, Be, Cu, Ag etc.
Effusion cells with conical shaped crucibles are specially optimized for doping applications. If two (or more) dopant materials shall be evaporated, DDS dual dopant cluster sources can be used.
Three different crucible sizes are available. Dimensions of these crucibles are shown in the figures on the right.
Technical Data
| Filament | standard Ta wire filament (SF) |
| Thermocouple, Temperature sensor (other types on request) | Type C |
| Operating temperature | 200-1400°C |
| Outgassing temperature | 1500°C |
| Bakeout temperature | 250°C |
| Cooling / water cooling | separate cooling shroud |
| Crucibles | 2, 5, or 12 cm³; PBN, PG crucibles, other materials on request |
| Options | integrated rotary shutter (S) |
Specific Data
For general information on CF mounting flanges see Flange and Gasketdimensions.| Product | Flange [CF] | Nominal capacity [cm³] | Lip diameter [mm] | Shutter | Filament type | Thermocouple type | UHV dimensions [mm] specify L with order | |
|---|---|---|---|---|---|---|---|---|
| DEZ | 40 | 2 | 22 | S | SF, CL | C | LxxxD34 | |
| DEZ | 40 | 5 | 27 | S | SF, CL | C | LxxxD36 | |
| DEZ | 40 | 12 | 36 | S | SF, CL | C | LxxxD36 | |
Example: DEZ 40-5-27-S-SF-C-P-L277D36 is a standard doping effusion cell on DN40 CF flange with 5cm³ conical PBN crucible, shutter, standard filament, type C thermocouple and UHV-length 277mm.
