GaAs SI-VGF
Grade
SI-VGF = semi-insulating single crystal, vertical gradient freeze
Pick when low dislocation density (EPD <5×10³ cm⁻²) and low residual stress matter — epi-ready device substrates and large low-wavefront-distortion optics.
Values for the SI-VGF condition
Other GaAs tempers and conditions
GaAs is listed in 4 conditions; see the grade overview at GaAs.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Poly-GaAs | Cheapest form — synthesised charge for crystal growth and low-cost thick IR blanks; grain boundaries scatter light and reduce strength, so not for high-power laser optics. | — | 55 | 0 | 590 HV | 48 W/m·K |
SI-LECDefault Semi-insulating single crystal, liquid encapsulated Czochralski | Standard undoped semi-insulating crystal for CO2-laser windows, IR optics and microwave/MMIC substrates. | — | 70 | 0 | 600 HV | 55 W/m·K |
Si-doped conductive single crystal | Conductive substrate grade for LEDs, laser diodes and solar cells; not used for IR windows because free-carrier absorption kills 10.6 µm transmission. | — | 72 | 0 | 620 HV | 45 W/m·K |
SI-VGFThis page Semi-insulating single crystal, vertical gradient freeze | Pick when low dislocation density (EPD <5×10³ cm⁻²) and low residual stress matter — epi-ready device substrates and large low-wavefront-distortion optics. | — | 80 | 0 | 600 HV | 55 W/m·K |
What is GaAs SI-VGF?
GaAs SI-VGF is GaAs in the SI-VGF grade — pick when low dislocation density (EPD <5×10³ cm⁻²) and low residual stress matter — epi-ready device substrates and large low-wavefront-distortion optics. GaAs SI-VGF has a tensile strength of 80 MPa (11.6 ksi), stronger than 79% of glass grades. Elongation at break is 0% and the elastic modulus is 85.5 GPa (12.4 Msi). GaAs SI-VGF has a density of 5.32 g/cm³ (0.192 lb/in³), heavier than 92% of glass grades. It melts at 1,238°C (2,260 °F). SI-LEC is the default condition FabDigit quotes; SI-VGF is available on request or by drawing note.
Advantages
- Conducts heat well — 55 W/m·K (31.8 BTU/hr·ft·°F), better than 93% of glass grades
- Easy to machine — 35/100, better than 77% of glass grades
Limitations
- High embodied carbon — 130 kg CO₂/kg, worse than 97% of glass grades
- Heavy — 5.32 g/cm³ (0.192 lb/in³), worse than 92% of glass grades
- Low fracture toughness — 0.46 MPa·√m (0.419 ksi·√in), worse than 76% of glass grades
GaAs SI-VGF properties
Typical room-temperature values for GaAs SI-VGF; 15 are specific to this condition. Other listed values are GaAs reference data and may not represent this condition. Bars are the position among glass grades.
Physical5
GaAs SI-VGF has a density of 5.32 g/cm³ (0.192 lb/in³), heavier than 92% of glass grades. It melts at 1,238°C (2,260 °F).
Mechanical13
GaAs SI-VGF has a tensile strength of 80 MPa (11.6 ksi), stronger than 79% of glass grades. Elongation at break is 0% and the elastic modulus is 85.5 GPa (12.4 Msi).
Thermal5
GaAs SI-VGF is rated for continuous service to 460°C (860 °F). It conducts heat at 55 W/m·K (31.8 BTU/hr·ft·°F), better than 93% of glass grades. Thermal expansion is 5.7 µm/m·K (3.17 µin/in·°F).
Electrical5
GaAs SI-VGF is an electrical insulator with a dielectric strength of 40 kV/mm (1,016 V/mil) and a resistivity of 3,000,000 Ω·m.
Chemical & Environmental2
Corrosion resistance is good (55/100), worse than 74% of glass grades.
Sustainability4
Producing a kilogram of GaAs SI-VGF takes about 2,000 MJ of energy and emits 130 kg of CO₂ — more than 97% of glass grades. Typical recycled content is 5%.
Manufacturability2
GaAs SI-VGF's machinability is fair (35/100, better than 77% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with GaAs SI-VGF
Is GaAs easy to machine?
Diamond wire saw / ID saw and diamond lapping only; single-point diamond turning works in ductile regime, but {110} cleavage means edge chipping — always chamfer and use full arsenic-dust extraction.
Can GaAs be welded?
Not weldable; joined by optical contacting, epoxy/indium bonding or metallised (AuGe/Ni/Au) soldering into mounts.
Can GaAs be formed, bent or molded?
No plastic forming — shape is set by melt growth (LEC/VGF) followed by slicing, grinding and polishing; complex profiles are ground, not pressed.
What surface finishes work on GaAs?
CMP to epi-ready/laser-grade finish, then multilayer AR coating (ThF₄/ZnSe or DLC) is essential since each uncoated surface reflects ~28%.
GaAs chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Gastoichiometric 1:1 atomic with As | 48 – 48.4 | 48.2 |
| Cresidual carbon ~1×10¹⁵–1×10¹⁶ cm⁻³, compensates EL2 in SI material | ≈ 2×10⁻⁸ | 2×10⁻⁸ |
| Siintentional dopant only in n-type grade (1×10¹⁷–5×10¹⁸ cm⁻³) | ≈ 1×10⁻⁷ | 1×10⁻⁷ |
| Asmelt grown near-stoichiometric; slight As-rich melt typical | ≥ 51.6 (balance) | — |
GaAs SI-VGF — frequently asked
What is GaAs SI-VGF used for?
GaAs SI-VGF is typically used for CO2 laser optics, IR windows/lenses, optoelectronic device substrates and laser diode substrates. In short: rugged 10.6 µm window; stronger than ZnSe; semi-insulating IR substrate.
What is the tensile strength of GaAs SI-VGF?
GaAs SI-VGF has a typical tensile strength of 80 MPa (11.6 ksi) — stronger than 79% of glass grades. Strength varies by condition: see the 4 listed tempers.
Is GaAs SI-VGF easy to machine?
Not especially — machinability is rated fair (35/100, better than 77% of glass grades). Diamond wire saw / ID saw and diamond lapping only; single-point diamond turning works in ductile regime, but {110} cleavage means edge chipping — always chamfer and use full arsenic-dust extraction.
Can GaAs SI-VGF be welded?
Not weldable; joined by optical contacting, epoxy/indium bonding or metallised (AuGe/Ni/Au) soldering into mounts.
What surface finishes work on GaAs SI-VGF?
CMP to epi-ready/laser-grade finish, then multilayer AR coating (ThF₄/ZnSe or DLC) is essential since each uncoated surface reflects ~28%.
Can GaAs SI-VGF be formed, bent or molded?
No plastic forming — shape is set by melt growth (LEC/VGF) followed by slicing, grinding and polishing; complex profiles are ground, not pressed.
What is the maximum service temperature of GaAs SI-VGF?
GaAs SI-VGF is rated for continuous use to about 460°C (860 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- NSM Archive — Physical Properties of Gallium Arsenide — Ioffe Institute (2001)
- Gallium Arsenide (GaAs) Optical Material Data — Crystran Ltd (2023)
- Handbook of Optical Constants of Solids — Academic Press (Palik, ed.) (1998)
- Semi-Insulating GaAs Substrate Specification (LEC / VGF) — Freiberger Compound Materials / AXT Inc. (2023)
- ASM Engineered Materials Handbook Vol. 4: Ceramics and Glasses — ASM International (1991)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.