Tubular heating element

molybdenumtungsten

Product overview
Components for epitaxial processes (MOCVD and MBE) used in LED chips, transistors, solar cells and other optoelectronic devices. Parts are manufactured in refractory metals (molybdenum, tungsten) and special alloys for use in reactor chambers exposed to extreme temperatures and vacuum conditions. Plansee supplies a wide range of reactor parts including shields, gas collectors and heating elements.

Your advantages at a glance

• FEM (finite element method) simulation for thermal optimisation
• Custom designs and tailored manufacturing
• Patented tungsten‑based porous coating
• Lower required operating temperature due to increased emissivity
• Extended service life and reduced replacement frequency
• Higher yield per coating cycle

Applications and performance
Heating elements in MOCVD systems can reach approximately 2000°C. Plansee offers over 50 different components for MOCVD and related epitaxial systems, available as OEM parts or spare parts. Design improvements and FEM‑based optimisation focus on achieving homogeneous temperature distribution in the reactor chamber to improve coating uniformity and process yield.

Coating and increased service life
Plansee's patented tungsten‑based porous coating raises effective surface area and surface emissivity of heating elements. Higher emissivity reduces the necessary operating temperature for a given thermal output and extends component lifetime by several months, lowering total operating costs.

Materials resistance table
Medium | Molybdenum | Tungsten
Ammonia gas | Up to 1000°C (1273 K) — no reaction; above 1000°C — possible surface nitriding | Up to 1000°C (1273 K) — no reaction; above 1000°C — possible surface nitriding
Noble gases | Up to the highest temperatures — no reaction | Up to the highest temperatures — no reaction
Carbon dioxide | Oxidation above 1200°C (1473 K) | Oxidation above 1200°C (1473 K)
Carbon monoxide | Oxidation above 1400°C (1673 K) | Oxidation above 1400°C (1673 K)
Hydrocarbons | Carburation above 1100°C (1373 K) | Carburation above 1200°C (1473 K)
Air and oxygen | Oxidation above 400°C (673 K); sublimation above 600°C (873 K) | Oxidation above 500°C (773 K); sublimation above 850°C (1123 K)
Nitrogen | Up to the highest temperatures — no reaction (applies to pure molybdenum) | Up to the highest temperatures — no reaction (applies to pure tungsten)
Water vapor | Oxidation above 700°C (973 K) | Oxidation above 700°C (973 K)
Hydrogen | Up to the highest temperatures — no reaction (observe dew point) | Up to the highest temperatures — no reaction (observe dew point)

Additional material and process notes

• High purity: materials supplied with purity >99.97% to avoid contamination of semiconductor layers.
• Low vapor pressure: suitable for high and ultra‑high vacuum applications.
• Special alloys available (TZM, WVM, ML, WL) for improved creep resistance and dimensional stability under thermal cycling.
• Patented coating increases thermal emissivity, enabling lower operating temperatures and longer service life.

Characteristics / technical specifications

• Typical MOCVD heating element temperatures: up to ~2000°C (design and materials engineered for extreme heat)
• Materials: molybdenum, tungsten and specialized alloys (e.g. TZM, WVM, ML, WL)
• Melting points: molybdenum ≈ 2620°C; tungsten ≈ 3420°C
• Material purity: > 99.97%
• Low vapor pressure suitable for high / ultra‑high vacuum
• Patented tungsten‑based porous coating to increase surface emissivity
• FEM simulation for homogeneous temperature distribution and optimized component design
• More than 50 different MOCVD components available (shields, gas collectors, heating elements)