GaAs POLY
Grade
POLY = 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.
Values for the POLY 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 |
|---|---|---|---|---|---|---|
POLYThis page 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 |
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 POLY?
GaAs POLY is GaAs in the POLY grade — 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. GaAs POLY has a tensile strength of 55 MPa (7.98 ksi), stronger than 71% of glass grades. Elongation at break is 0% and the elastic modulus is 84 GPa (12.2 Msi). GaAs POLY 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; POLY is available on request or by drawing note.
Advantages
- Conducts heat well — 48 W/m·K (27.7 BTU/hr·ft·°F), better than 92% 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
- Needs corrosion protection — 50/100, worse than 80% of glass grades
- Low fracture toughness — 0.5 MPa·√m (0.455 ksi·√in), worse than 76% of glass grades
GaAs POLY properties
Typical room-temperature values for GaAs POLY; 16 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 POLY 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 POLY has a tensile strength of 55 MPa (7.98 ksi), stronger than 71% of glass grades. Elongation at break is 0% and the elastic modulus is 84 GPa (12.2 Msi).
Thermal5
GaAs POLY is rated for continuous service to 460°C (860 °F). It conducts heat at 48 W/m·K (27.7 BTU/hr·ft·°F), better than 92% of glass grades. Thermal expansion is 5.7 µm/m·K (3.17 µin/in·°F).
Electrical5
GaAs POLY is an electrical insulator with a dielectric strength of 40 kV/mm (1,016 V/mil) and a resistivity of 0.01 Ω·m.
Chemical & Environmental2
Corrosion resistance is fair (50/100), worse than 80% of glass grades.
Sustainability4
Producing a kilogram of GaAs POLY 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 POLY's machinability is poor (30/100, better than 71% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with GaAs POLY
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 POLY — frequently asked
What is GaAs POLY used for?
GaAs POLY 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 POLY?
GaAs POLY has a typical tensile strength of 55 MPa (7.98 ksi) — stronger than 71% of glass grades. Strength varies by condition: see the 4 listed tempers.
Is GaAs POLY easy to machine?
Not especially — machinability is rated poor (30/100, better than 71% 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 POLY 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 POLY?
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 POLY 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 POLY?
GaAs POLY 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.