High Temperature Effusion Cell HTEZ-W

• Compatible with most MBE systems
• Various crucible materials; crucible capacity 10 cm³
• No ceramic insulation parts in hot area
• Free-standing thick tungsten wire filament
• Clean operation in UHV up to 2000°C
• High reliability and long lifetime
• Water cooled current contacts  Datasheet

Introduction

The High Temperature Effusion Cells HTEZ are designed for clean UHV operation up to 1900°C. This is accomplished by a self-supporting tungsten filament.

Equipped with a free-standing filament of thick tungsten wire, the model HTEZ-W is capable of reaching 2000°C or even more. The main parts of the heating system are shown in the figure on the right.

In contrast to the HTS sources, HTEZ-W cells predominantly heat the crucible from the side. The deep crucible design allows operation in angled port positions, combining large capacity with high temperature operation.

Like in the standard WEZ heating system, only selected refractory metals are used in the hot zone. On account of the elevated operating temperatures, the filaments are made of tungsten.

While insulating PBN ceramic parts are fully shielded by tantalum plates to prevent outgassing during operationin in HTEZ cells, the HTEZ-W cells work completely without any additional ceramic insulation.

HTEZ-W cells are highly efficient, enable a very reproducible temperature measurement and allow precise adjustment as the thermocouple measuring point is close to the crucible.

Well-designed tungsten filaments have proved to be very stable, thus safeguarding a long lifetime even when working on the upper limit of the cell.

The figure on the right provides a view into the orifice of a hot HTEZ-W cell. The red-hot filament is clearly visible.

The HTEZ-W design allows mounting ceramic crucibles (e.g. BeO) directly into the cell without outer metal crucible. In this way a higher temperature of the evaporation material in the crucible can be achieved.

Application

The HTEZ-W is designed for evaporation or sublimation of low vapor pressure elements and compounds at temperatures up to 2000°C, e.g. for materials like Fe, Cr, Ni, Co, V, Pt, Ti, La etc. Typical applications are surface science analysis or thin film deposition of magnetic or oxide layers.

The maximum operating temperature of the HTEZ-W may be limited by the crucible choice, e.g. to 1600°C with PBN. Furthermore, possible reactions of evaporants with the crucible material should be taken into account, which may also reduce the maximum advisable temperature.

Please refer to the Selection Guide for material data and decision-making advice.

Technical Data

Crucibles

Standard crucible sizes is 10 cm³. Different crucible materials such as Al₂O₃ , BeO, Ta, W, pyrolytic graphite (PG) and pyrolytic boron nitride (PBN) can be applied. For detailed information on crucibles see Crucibles .

Please specify crucible material upon ordering, or inquire for our recommendation.

Dimensions

Specific data

For general information on CF mounting flanges see Flange and Gasketdimensions .

** no standard, please inquire for your particular solution *** specify UHV length L with order

Product code: e.g. HTEZ-W 40-10-32-T-L250D36 is a high temperature effusion cell on DN40CF-flange with 10 cm³ crucible (lip Ø 32 mm), Tantalum crucible, in-vacuum length 250 mm and diameter 36 mm.