CVD and HPHT diamond

The two material forms we supply each have distinct strengths. We select the growth route and grade for every part based on its application requirements.

Thermal conductivity: Up to 2,200 W/m·K
CVD wafers: Up to Ø 100 mm
HPHT plates: Up to 8 × 8 mm
Material options: 7 listed below

Growth routes

How each one is made, and what it is for.

CVD polycrystalline

Deposited layer by layer from a carbon-bearing gas in a plasma reactor, then separated from the growth substrate to produce free-standing wafers up to Ø 100 mm.

The choice when a part needs area: large heat spreaders, optical windows and wear surfaces that can be laser-cut to almost any outline.

Thermal conductivity: 1,000–2,000 W/m·K
Wafer size: Up to Ø 100 mm
Thickness: 0.1–2.0 mm

Best for

01Heat spreaders above a few millimetres
02Optical and microwave windows
03Large wear surfaces

HPHT single crystal

Grown from a metal solvent at high pressure and temperature, the conditions under which natural diamond forms.

The choice for small parts that need the highest, most uniform conductivity or a well-defined crystallographic edge.

Thermal conductivity: Up to 2,200 W/m·K
Plate size: Up to 8 × 8 mm
Grain boundaries: None

Best for

01Submounts under single emitters
02Precision cutting edges
03Small precision wear parts

Comparison

Side by side.

	CVD polycrystalline	HPHT single crystal
Structure	Polycrystalline, columnar grains	Single crystal
Thermal conductivity	1,000–2,000 W/m·K by grade	Up to 2,200 W/m·K
Largest part	Ø 100 mm wafer	About 8 × 8 mm plate
Optical use	Optical grades for UV, visible, IR and RF applications	Type IIa for optics; Type Ib is yellow
Edge quality	Laser-cut, limited by grain size	Crystal edge, can be sharpened
Cost	Lowest per area for large parts	Lowest for small precision parts

Grades

Standard material options.

Thermal grades are named by their minimum room-temperature conductivity. Optical, mechanical and other material options are selected by application.

Grade	Material	Key value	Typical use
Thermal 1000	CVD	≥ 1,000 W/m·K	Power modules, cost-sensitive spreaders
Thermal 1500	CVD	≥ 1,500 W/m·K	GaN RF amplifiers, laser bars
Thermal 1800	CVD	≥ 1,800 W/m·K	High heat-flux laser diodes
Thermal 2000	CVD	≥ 2,000 W/m·K	Highest heat-flux devices
Single crystal	HPHT	Up to 2,200 W/m·K	Single-emitter submounts, precision parts
Optical	CVD	< 0.07 cm⁻¹ at 10.6 µm	CO₂ laser and IR windows
Mechanical	CVD / HPHT	70–100 GPa hardness	Wear parts and tooling

Representative values. The final specification is confirmed in the quotation.

Reference

Properties of diamond.

Representative intrinsic values at room temperature for the early design calculations that come before a finished drawing.

Density: 3.52g/cm³
Young's modulus: 1,050GPa
Hardness: 70–100GPa
Thermal expansion: 1.0ppm/K at 300 K
Band gap: 5.47eV
Refractive index: 2.41visible; 2.38 at 10.6 µm
Electrical resistivity: ≥ 10¹²Ω·cm, grade-dependent
Dielectric constant: 5.7

Not sure which grade fits?

Send the application and the operating conditions. We’ll recommend CVD or HPHT and the grade that meets the requirement at the lowest cost.

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