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HTS 40-5, high temperature source on DN40 (O.D.2.75") CF flange,
with 5 cm³ crucibles made of BeO and PG (pyrolytic graphite)

• Compatible with all MBE systems
• Various crucible sizes and materials,
  crucible capacities 5, 25, 100 cm³
• Clean operation in UHV up to 2000°C
• Ultra high purity pyrolytic graphite (PG) filament
• Water cooled electrical contacts
• Inner filament shielding with PG parts
• No ceramic parts in the hot zone

The High Temperature Source - HTS - is designed for evaporation of materials with very low vapour pressure.

Many high temperature sources used e.g. for boron doping in silicon MBE are heated by a tungsten wire filament which becomes very fragile in combination with a pyrolytic graphite crucible. The use of ceramic and metal parts in the hot zone can cause outgassing of significant amounts of CO and other undesirable residual gases which are not tolerable in Si MBE.

The HTS from MBE-Komponenten GmbH is equipped with a high purity pyrolytic graphite (PG) crucible which is radiation heated by a high purity PG filament. Maximum operation temperature is about 2000°C. This high temperature source is based on the concept of our carbon sublimation source SUKO.

The free standing pyrolytic graphite filament and the crucible are completely surrounded with PG parts. PG screws, PG washers, PG contacts, PG plates and a PG tube are used to protect the very hot filament. There are no ceramic or metallic parts in the hottest zone. The whole cell is surrounded by extensive tantalum outer radiation shielding.

Main parts of the HTS, schematic

A very effective internal water cooling of the electrical contacts avoids overheating of these parts, allows rapid change of the flux rate and provides a short adjusting time.

It is recommended to use the HTS in combination with a separate water or LN₂ cooling shroud to avoid overheating of the stainless steel parts of the UHV chamber. MBE-Komponenten GmbH provides different cooling shrouds with integrated shutter.

The main parts of the HTS source are shown in the figures on the right.

Pyrolytic graphite (PG) parts of the HTS

Application

Typical applications of the HTS are:

• evaporation of elemental boron for p-type doping in Si MBE
• evaporation of Ge in Si/Ge MBE (special Ge effusion cell with PBN crucible and Si top orifice plate)
• evaporation of CaF₂, Ti, Ni, Cr, Au, Er, La, etc.

Results from p-type doping in Si MBE, using the HTS for sublimation of boron, are shown in the figure nearby.
The diagram is a typical example for the boron doping concentration as a function of the electrical current, for HTS 63.

1. Prof. I. Eisele, Univ. d. Bundeswehr Munich/Neuperlach
2. Prof. G. Abstreiter, Walter Schottky Institute Garching, Germany
3. Prof. E. Kasper, IHT Univ. Stuttgart, Germany

Typical boron doping levels achieved with HTS 63

Technical Data

Crucibles

Standard crucible sizes for our HTS are 5, 25 and 100 cm³. Other dimensions and different shapes on request.
Beside the pyrolytic graphite (PG) crucible, BeO, PBN or W are used as crucible material, too. The maximum operating temperature may be reduced depending on the crucible material, e.g. for PBN max. 1500°C. For detailed information see page "Crucibles".

The second number in our Product-code is the crucible capacity [in cm³]. Please also specify the crucible material when ordering!

Dimensions

For general information on CF mounting flanges see "Flange and Gasket Dimensions".

Specific Data

 LAST UPDATE: NOVEMBER, 2004

© 2003 Dr. Eberl MBE-Komponenten GmbH