Ge SEMI
Grade
SEMI = semiconductor/substrate-grade single crystal
Ga- or Sb-doped <100>/<111> wafers for III–V epitaxy and multi-junction solar cells, not for IR imaging optics.
Values for the SEMI condition
Other Ge tempers and conditions
Ge is listed in 5 conditions; see the grade overview at Ge.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SC-OPTDefault Optical-grade single crystal | Standard choice for thermal-imaging lenses, windows and domes needing best 8–12 µm transmission and diamond-turnable surfaces. | — | 70 | 0 | 800 HV | 59 W/m·K |
High-resistivity / near-intrinsic single crystal | Pick when minimum free-carrier absorption is critical — long path lengths, THz components, CO2-laser and high-power IR optics. | — | 70 | 0 | 800 HV | 60 W/m·K |
SEMIThis page Semiconductor/substrate-grade single crystal | Ga- or Sb-doped <100>/<111> wafers for III–V epitaxy and multi-junction solar cells, not for IR imaging optics. | — | 70 | 0 | 800 HV | 55 W/m·K |
Single crystal with AR / diamond-like-carbon coating | Use for any real system: multilayer AR (and DLC on the outer face) removes the 36 %/surface reflection and adds rain/sand erosion resistance. | — | 70 | 0 | 1,800 HV | 59 W/m·K |
Polycrystalline optical germanium | Lower-cost, large-diameter windows and non-diamond-turned optics where grain boundaries in the surface are acceptable. | — | 75 | 0 | 790 HV | 57 W/m·K |
What is Ge SEMI?
Ge SEMI is Ge in the SEMI grade — ga- or Sb-doped <100>/<111> wafers for III–V epitaxy and multi-junction solar cells, not for IR imaging optics. Ge SEMI has a tensile strength of 70 MPa (10.2 ksi), stronger than 76% of glass grades. Elongation at break is 0% and the elastic modulus is 103 GPa (14.9 Msi). Ge SEMI has a density of 5.32 g/cm³ (0.192 lb/in³), heavier than 93% of glass grades. It melts at 938°C (1,720 °F). SC-OPT is the default condition FabDigit quotes; SEMI 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
- Stiff — 103 GPa (14.9 Msi), better than 81% of glass grades
- Easy to machine — 40/100, better than 80% 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 93% of glass grades
Ge SEMI properties
Typical room-temperature values for Ge SEMI; 16 are specific to this condition. Other listed values are Ge reference data and may not represent this condition. Bars are the position among glass grades.
Physical4
Ge SEMI has a density of 5.32 g/cm³ (0.192 lb/in³), heavier than 93% of glass grades. It melts at 938°C (1,720 °F).
Mechanical13
Ge SEMI has a tensile strength of 70 MPa (10.2 ksi), stronger than 76% of glass grades. Elongation at break is 0% and the elastic modulus is 103 GPa (14.9 Msi).
Thermal5
Ge SEMI is rated for continuous service to 400°C (752 °F). It conducts heat at 55 W/m·K (31.8 BTU/hr·ft·°F), better than 93% of glass grades. Thermal expansion is 5.9 µm/m·K (3.28 µin/in·°F).
Electrical3
Ge SEMI has an electrical resistivity of 0.005 Ω·m.
Chemical & Environmental2
Corrosion resistance is good (55/100), worse than 74% of glass grades.
Sustainability3
Producing a kilogram of Ge SEMI takes about 2,000 MJ of energy and emits 130 kg of CO₂ — more than 97% of glass grades. Typical recycled content is 30%.
Manufacturability2
Ge SEMI's machinability is fair (40/100, better than 80% of glass grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Ge SEMI
Is Ge easy to machine?
Grind and lap with diamond abrasives, then single-point diamond turn with light depths of cut and copious coolant; it is brittle with {111} cleavage, so edges must be chamfered and clamping loads kept low.
Can Ge be welded?
Not weldable — mount by elastomeric bonding, low-stress epoxy or spring/retainer rings that accommodate its 5.9 µm/m·K CTE.
Can Ge be formed, bent or molded?
Shaped only by crystal growth (Czochralski/casting) plus subtractive optical finishing; no plastic forming at room temperature.
What surface finishes work on Ge?
Polishes to sub-nanometre roughness; virtually always finished with multilayer 8–12 µm AR coatings and a DLC or hard-carbon layer on exposed outer surfaces.
Ge 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.
| Element | Spec limit (wt %) |
|---|---|
| Sbppb-level n-type dopant deliberately added in some crystals to set resistivity | ≈ 0 |
| Gezone-refined 5N–6N feedstock; optical grade specified by resistivity (5–40 Ω·cm) and dislocation/etch-pit density rather than by trace chemistry | ≥ 100 (balance) |
Ge SEMI — frequently asked
What is Ge SEMI used for?
Ge SEMI is typically used for thermal imaging lenses, IR windows, AR-coated Ge optics and laser optics. In short: standard 8–12 µm lens material; high index, high density; limited to ~100 °C service.
What is the tensile strength of Ge SEMI?
Ge SEMI has a typical tensile strength of 70 MPa (10.2 ksi) — stronger than 76% of glass grades. Strength varies by condition: see the 5 listed tempers.
Is Ge SEMI easy to machine?
Not especially — machinability is rated fair (40/100, better than 80% of glass grades). Grind and lap with diamond abrasives, then single-point diamond turn with light depths of cut and copious coolant; it is brittle with {111} cleavage, so edges must be chamfered and clamping loads kept low.
Can Ge SEMI be welded?
Not weldable — mount by elastomeric bonding, low-stress epoxy or spring/retainer rings that accommodate its 5.9 µm/m·K CTE.
What surface finishes work on Ge SEMI?
Polishes to sub-nanometre roughness; virtually always finished with multilayer 8–12 µm AR coatings and a DLC or hard-carbon layer on exposed outer surfaces.
Can Ge SEMI be formed, bent or molded?
Shaped only by crystal growth (Czochralski/casting) plus subtractive optical finishing; no plastic forming at room temperature.
What is the maximum service temperature of Ge SEMI?
Ge SEMI is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASM Handbook Vol. 2 — Properties of Nonferrous Alloys and Special-Purpose Materials (germanium) — ASM International (1990)
- Handbook of Optical Constants of Solids — Academic Press (1998)
- CRC Handbook of Chemistry and Physics, 97th ed. — CRC Press (2016)
- Germanium (Ge) IR optical material datasheet — II-VI / Coherent, Umicore, Crystran (2023)
- Landolt-Börnstein: Semiconductors — Group IV Elements, elastic constants of Ge — Springer (2001)
- Mineral Commodity Summaries — Germanium (recycling and price) — USGS (2025)
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.