Get in Touch

We’re here to help - please let us know how we can do so.

Contact Us

Shop Online

You can now purchase our products online!


CdTe Cadmium Telluride Technical Data

Download Technical Sheet [PDF]

Summary Description

Cadmium telluride is a medium refractive index material (2.67 @ 10 microns) with excellent long wavelength transmission in the infrared. It is non-hygroscopic with  very good chemical resistance. Since it is a multiple  crystalline material, some lots of material can exhibit  large Mie scattering at the shorter wavelengths. It has  been marketed in the past as IRTRAN-6.

Windows, including those used for cooled infrared  detectors, must be thicker than those made from other materials because of the low tensile strength.


  1. Non-hygroscopic
  2. Good chemical resistance except for the very strong acids, for example, HNO3
  3. Excellent spectral range


  1. Expensive
  2. Brittle
  3. Low tensile strength
  4. Mie scattering can reduce the transmission of CdTe in the shorter wavelengths
  5. Multi-crystalline structure can vary on a lot basis. This can produce a variability in both the short wavelength transmission and strength of the material
  6. CdTe is toxic and expensive

Far-IR Transmission – 1 mm thick CdTe Window


Far-IR Transmission – 4 mm thick CdTe Window


CdTe also transmits at wavelengths longer than 80 microns at very low temperatures. However the transmission is temperature dependent and Si is generally a better choice for a window for this spectral region.

Physical Data1

Melting Point: 1092 °C
Density: 6.2 g/cm3
Solubility in H2O: Insoluble
Hardness: 56 kg/mm2
Appearance: Black, cubic crystalline material, either polished or satin finish

Refractive Index2

2.1 2.71**
2.5 2.70**
3.0 2.685
4.0 2.682
5.0 2.685
6.0 2.682
7.0 2.680
8.0 2.677
9.0 2.675
10.0 2.672
12.5 2.665
15.0 2.657
17.5 2.646
20.0 2.633
22.0 2.622

Specific index listed. Generic: 2.67 @ 10 microns
**Sopra S. A Material Data Base

Spectral Range

Short Wavelength Limit: 17,000 cm-1 (1 mm)
Long Wavelength Limit: 313 cm-1 (1 mm), 340 cm-1 (4 mm)


CdTe can be coated with a BBAR (Broad Band Antireflection) coating. However, this coating will not improve transmission at wavelengths longer than about 16 microns.

Typical Uses

  • IR detector windows-CdTe absorbs HeNe laser at 6328. This makes it an attractive window for MCT detectors used in FT-IR systems.
  • Liquid cell windows


Short and Long Wavelength Ranges for which transmissivity is greater than 50% of stated crystal thickness.

  1. F. Buch and C. N. Ahlqvist, The yield strength of polycrystalline CdTe as a function of grain size, Material Science and Engineering 13, 194–196 (1974).
  2. A.G. DeBell et al. Cryogenic refractive indices and temperature coefficients of cadmium telluride from 6 μm to 22 μm, Appl. Opt. 18, 3114 –3115 (1979).

Get in Touch

We’re here to help - please let us know how we can do so.

Contact Us

Shop Online

You can now purchase our products online!