Germanium is a chemical element with the symbol Ge and atomic number 32. It is a lustrous, hard-brittle, grayish-white metalloid in the carbon group, chemically similar to its group neighbours silicon and tin. Pure germanium is a semiconductor with an appearance similar to elemental silicon. Like silicon, germanium naturally reacts and forms complexes with oxygen in nature.
Germanium sputtering targets are made of 5N germanium crystals, due to its wide transmission range in the infrared and opaqueness in the visible light regions, germanium sputtering targets are used for depositing germanium thin film on the optic of thermal imaging camera. Such optics are usually working in the 8 to 14 micron range for passive thermal imaging and for hot-spot detection in military, mobile night vision, and fire fighting applications. It’s also used in infrared spectroscopes and other optical equipment that require extremely sensitive infrared detectors.
But as germanium thin film has a very high refractive index (4.0), so it must be coated with a anti-reflection film.

Target Materials: Germanium Ge
Crystal structure: Monocrystalline, polycrystalline
Purity: 5N, 6N
Conduction Type: N type
Resistivity: 0.03-50Ω.cm
Refractive index (10um): 4.0026
Absorption coefficient (/cm): ≤ 0.03
Optical transmittance: 46%
Surface finish: Ra 1.6um
Round target size: Diameter ≤ 450mm, thickness ≥ 0.5mm
Rectangle target size: 205 x 205mm max

Following is a typically Certificate of analysis of 5N Germanium Sputtering Target.
Analytical Methods:
1. Metallic elements were analyzed by GDMS;
2. Gas elements were analyzed by LECO.