Germanium
metalloidProperties
| Property | Value |
|---|---|
| Atomic Mass | 72.63 amu |
| Category | metalloid |
| Group | 14 |
| Period | 4 |
| Electron Configuration | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p2 |
| Electronegativity | 2.01 (Pauling) |
| Oxidation States | 4, 2 |
| Melting Point | 1211.4 K (938.3 °C) |
| Boiling Point | 3106 K (2832.8 °C) |
| Density | 5.323 g/cm³ |
| Discovered By | Clemens Winkler (1886) |
About Germanium
Germanium was the original semiconductor — Bardeen, Brattain, and Shockley's 1947 point-contact transistor at Bell Labs was made of n-type germanium because the purification chemistry for silicon hadn't been solved yet. Once zone refining made 99.9999999% silicon practical in the 1950s, germanium got pushed aside for digital logic. It came back through the side door. Germanium has roughly three times the electron mobility of silicon, and SiGe alloys grown epitaxially on silicon strain the lattice in ways that boost transistor speed without breaking the existing fab toolchain — every modern smartphone radio uses SiGe heterojunction bipolar transistors for that reason. Germanium also has a bandgap (0.67 eV) that lines up with infrared, making it the standard window and lens material for thermal-imaging cameras and CO₂ laser optics. Doped with a few parts per million of GeO₂, silica fiber gets the refractive-index profile needed for single-mode telecom fiber, which is how nearly every long-haul data signal in the world spends part of its life passing through germanium. High-purity hyperpure germanium crystals are also the detector of choice for gamma spectroscopy.
Fun Fact
The very first transistor — the device that made modern computing possible — was built using germanium in 1947, and Mendeleev had predicted germanium's existence and properties 76 years earlier with astonishing accuracy, calling it 'eka-silicon.'
Common Uses
- Infrared optics and thermal imaging camera lenses
- Silicon-germanium (SiGe) transistors for high-speed electronics
- Fiber optic cable production as a dopant
- PET plastic polymerization catalyst
- Gamma-ray detectors for nuclear and space applications