Glossary
Diamond materials, in plain words.
Short definitions of the terms used across this site, from CVD growth to metallization and spectroscopy.
A
- ATR (attenuated total reflection)
- ATR is a spectroscopy technique where light reflects inside a crystal and probes a sample pressed against its surface. Diamond is used because it is hard, chemically inert and broadly transparent.
- AuSn solder
- AuSn solder is a gold–tin alloy used to join components without flux. It melts at a defined temperature and gives a strong joint, so it is often used for laser and RF devices attached to metallized diamond.
B
- BDD electrode
- A BDD electrode is a boron-doped diamond electrode. It is conductive, chemically robust and has a wide electrochemical window. It is used in water treatment and electroanalysis.
- Beam splitter
- A beam splitter divides a light beam into transmitted and reflected parts. Diamond beam splitters are used where high power, broad wavelength range or durability are needed.
- Boron-doped diamond
- Boron-doped diamond contains boron atoms added during growth. Boron acts as an acceptor, making diamond electrically conductive. It is used for electrodes and some electronic structures.
- Bow and warp
- Bow and warp describe how far a wafer deviates from flat. Bow is the centre deviation, and warp is the overall variation. Both affect bonding, lithography and the stress in bonded stacks.
C
- Composite (Cu–diamond)
- A copper–diamond composite embeds diamond particles in a copper matrix. It aims to combine high conductivity with controllable expansion. Properties depend on formulation and processing, not diamond content alone.
- Crystal orientation
- Crystal orientation is the direction of the crystal lattice relative to the polished face, such as (100) or (111). It influences growth, polishing, cleaving and properties, so it appears on drawings.
- CTE (coefficient of thermal expansion)
- CTE describes how much a material changes size as temperature changes. Joined materials with different CTEs stress each other during heating and cooling, so matching or balancing CTE improves reliability.
- CVD (chemical vapour deposition)
- CVD is a process that builds a solid film or crystal from a reacting gas. In diamond, carbon from a gas mixture deposits on a substrate, forming single-crystal or polycrystalline material of controlled purity.
D
- Diamond-on-silicon
- Diamond-on-silicon is a diamond layer carried on a silicon support rather than a free-standing diamond part. It allows diamond's heat conduction to be used in silicon-compatible formats.
- Direct-bonded copper
- Direct-bonded copper joins copper to a ceramic-like substrate without a separate adhesive layer. On diamond it forms electrical patterns and thermal paths, so bond quality and cycling are key.
E
- Electrochemical window
- The electrochemical window is the voltage range in which an electrode works without breaking down the electrolyte. Boron-doped diamond has a wide window, enabling reactions that other electrodes cannot reach.
- Electronic grade
- Electronic grade diamond is selected for low, controlled impurities and defects so electrical behaviour is predictable. The relevant limits and test methods depend on your device and must be stated.
- Epitaxy
- Epitaxy is growth of a crystalline layer on a crystal substrate so the layer follows the substrate's orientation. Epitaxial diamond layers are used where doping or purity must differ from the substrate.
F
- FTIR
- FTIR is Fourier-transform infrared spectroscopy. It measures infrared absorption. In diamond it identifies impurities such as nitrogen and assesses how well the material transmits across the infrared range.
G
- GaN-on-diamond
- GaN-on-diamond places gallium nitride close to a diamond layer, by growth or bonding. The aim is to carry heat away from high-power transistors more effectively than a conventional substrate.
H
- Heat spreader
- A heat spreader is a component that moves heat sideways from a small source to a larger area. Diamond spreaders reduce hotspot temperature by distributing heat before it enters the cooler.
- HPHT
- HPHT is high-pressure, high-temperature synthesis. It grows diamond from carbon in conditions similar to natural formation, and is a different route from CVD. HPHT stones are commonly used for single-crystal parts.
L
- Laser flash analysis
- Laser flash analysis measures thermal diffusivity. A short pulse heats one face of a sample, and a detector records the temperature rise on the other. Conductivity is then calculated.
M
- Metallization
- Metallization is a thin metal layer applied to a surface for soldering, brazing or electrical contact. On diamond it provides a bondable face, because solder does not wet bare diamond.
- Miscut
- Miscut is the small angle between a crystal's polished face and its nominal crystal plane. It affects how layers grow on the surface, so epitaxy and device work usually specify it.
- MPCVD
- MPCVD is microwave plasma chemical vapour deposition. A microwave plasma activates the gas, and carbon deposits as diamond. The plasma is confined away from reactor walls, which supports high-purity growth.
N
- NV centre
- An NV centre is a nitrogen-vacancy defect in the diamond lattice: a nitrogen atom next to a missing carbon. Its spin can be read optically, which makes it useful for quantum sensing.
O
- Optical grade
- Optical grade diamond is selected for low absorption and scatter at a stated wavelength band. It does not mean identical transmission at every wavelength, so state the band and thickness.
P
- PCD (polycrystalline diamond)
- In tooling, PCD is sintered polycrystalline diamond: diamond grains consolidated with a binder onto a backing. It is a cutting-tool material, distinct from binder-free CVD polycrystalline diamond.
- Polycrystalline diamond
- Polycrystalline diamond is made of many small diamond grains. It can be grown as larger discs and plates than single crystals, and is widely used for heat spreaders, windows and wear parts.
R
- Raman spectroscopy
- Raman spectroscopy probes vibrations in a material using scattered laser light. In diamond it confirms the crystal phase, shows stress and detects any non-diamond carbon present.
S
- Single-crystal diamond
- Single-crystal diamond is one continuous lattice with no grain boundaries. This gives uniform, orientation-dependent properties, which suits optics, electronics, tools and sensing where crystal direction matters.
- Speaker dome
- A speaker dome is the thin, curved diaphragm of a tweeter. It must be stiff and light. Diamond domes push break-up resonance higher, which extends usable high-frequency range.
- Submount
- A submount is a base on which a laser or chip is mounted. It supports the device, provides electrical or thermal contact and conducts heat to the heat sink. Diamond submounts do this with very high conductivity.
- Surface roughness (Ra)
- Ra is the average deviation of a surface from its mean line. A lower Ra means a smoother surface. Required values depend on whether the face is optical, bonded or mechanical.
T
- Thermal boundary resistance
- Thermal boundary resistance is the resistance to heat flow across an interface between two materials. In diamond stacks it can limit performance as much as the diamond itself.
- Thermal conductivity
- Thermal conductivity measures how readily a material conducts heat. Diamond has a very high value, well above copper. Device temperature also depends on interfaces, geometry and cooling.
- Ti/Pt/Au stack
- A Ti/Pt/Au stack is a common metallization sequence. Titanium adheres to the surface, platinum acts as a diffusion barrier and gold provides a solderable finish. Stacks vary, so the sequence is agreed per project.
- Tool blank
- A tool blank is an unfinished piece of diamond prepared to be made into a cutting tool. Orientation, inclusions and edge allowance are specified before the final geometry is ground.
- TTV (total thickness variation)
- TTV is the difference between the thickest and thinnest points of a wafer or plate. It indicates thickness uniformity and matters for bonding, polishing and optical flatness.
X
- X-ray target
- An X-ray target is the material struck by an electron beam to produce X-rays. Diamond can support the target layer and conduct away the heat concentrated at the focal spot.
- XRD (X-ray diffraction)
- XRD measures how a crystal diffracts X-rays. In diamond it reveals orientation, lattice strain and crystal quality, which matters for seed crystals, epitaxy and tool blanks.
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