Germanium (Ge) Semiconductors

Topics Covered

Chemical Properties
Electrical Properties
Thermal, Mechanical and Optical Properties
Safety Information


Germanium is a Period 4 element belonging to Group 14, Block P. The electronic configuration of Germanium (Ge) is 3d10 4s2 4p2. Germanium is non-toxic. It is a hard, lustrous, grayish-white metalloid chemically similar to its group neighbors, tin and silicon. Germanium is mainly obtained from sphalerite but is also found in lead, silver and copper ores. Clemens Winkler discovered germanium in 1886.The name Germanium finds its origin from the latin word ‘Germania'.


Germanium finds applications in the following:

  • On doping with arsenic, gallium or other elements it is made use of in transistors for a large number of electronic applications.
  • Used as a phosphor in fluorescent lamps, alloying agent and catalyst.
  • Germanium and germanium oxide are transparent to the infrared and find applications in optical devices such as highly sensitive infrared detectors and infrared spectroscopes.
  • Germanium has a high refractive index and germanium oxides have diffraction properties that enable its use as a component in microscope objective and wide-angle lenses.
  • It finds applications in the front optic in thermal imaging cameras functioning in the 8-14 µm wavelength range for passive thermal imaging.
  • Germanium is also used for hot-spot detection in military, night vision system in cars, in the military and in fire fighting applications.
  • Germanium has recently been used in precious metal alloys. For example, in sterling silver alloys, germanium has been found to improve tarnish resistance, bring down fire-scale and considerably improve the response of the alloy to precipitation hardening. About 1.2% germanium is used in a sterling silver alloy commercially known as Argentium.
  • Highly pure germanium single crystal detectors can detect accurately radiation sources such as in airport security.
  • High-purity germanium crystals are used in gamma spectroscopy detectors and in the quest for dark matter.

Chemical Properties

The chemical properties of Germanium are provided in the table below:

Chemical Properties
Chemical Formula Ge
Molecular Weight 72.64
CAS No. 7440-56-4
Group IV
Band Gap 0.67 eV
Band Gap Type Indirect
Crystal Structure Diamond
Symmetry Group Oh7-Fd3m
Lattice Constant 5.658 Å

Electrical Properties

The electrical properties of Germanium are provided in the table below:

Electrical Properties
Intrinsic Carrier Concentration 2.4 x 1013 cm-1
Electron Mobility ≤ 3900 cm2 V-1 s-1
Hole Mobility ≤ 1900 cm2 V-1 s-1
Electron Diffusion Coefficient ≤ 100 cm2 s-1
Hole Diffusion Coefficient ≤ 50 cm2 s-1
Electrical Resistivity 46 Ωcm

Thermal, Mechanical and Optical Properties

The thermal, mechanical and optical properties of Germanium are provided in the tables below:

Mechanical Properties
Melting Point 938.25 °C
Density 5.323 g cm-3
Young's Modulus 103 GPa
Shear Modulus 41 GPa
Bulk Modulus 75 GPa
Specific Heat (@ 298 K) 0.31 J g-1 K-1
Thermal Properties
Thermal Conductivity 0.58 W cm-1 °C-1
Thermal Diffusivity 0.36 cm2 s-1
Thermal Expansion Coefficient 5.9x10-6 °C-1
Optical Properties
Refractive Index (589 nm @ 293 K) 4
Radiative Recombination Coefficient (@ 300 K) 6.4x10-14 cm3 s-1

Safety Information

Safety Information
GHS Hazard Statements H-315 – Causes skin irritation
H319- Causes serious eye irritation
H335-May cause respiratory irritation
Safety Precautions S 26-36/39

Source: AZoM

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