Germanium and silicon are both Group IV semiconductors, but silicon is far more widely used in modern electronics. This is largely due to several inherent disadvantages of germanium when compared to silicon, especially in high-volume and high-temperature applications.
1. Lower Thermal Stability
Germanium has a lower melting point (~937°C) than silicon (~1414°C). This limits its suitability for high-temperature processing and operation, making silicon the preferred material for most power and high-temperature electronic devices.
2. Narrower Bandgap
Germanium has a smaller bandgap (~0.66 eV) compared to silicon (~1.12 eV). While this allows high carrier mobility, it also results in:
- Higher leakage current
- Increased thermal noise
- Poor performance at elevated temperatures
This makes germanium less stable for standard semiconductor electronics.
3. Higher Cost and Limited Availability
Germanium is a rare element and is primarily obtained as a byproduct of zinc and coal processing. As a result:
- Raw material costs are significantly higher than silicon
- Supply is more limited and subject to market fluctuations
Silicon, by contrast, is abundant and inexpensive.
4. Inferior Native Oxide
Silicon forms a high-quality, stable native oxide (SiO₂) that is essential for MOSFET fabrication. Germanium oxide (GeO₂) is:
- Water-soluble
- Chemically unstable
- Unsuitable as a reliable insulating layer
This severely limits germanium’s use in modern CMOS manufacturing.
5. Higher Leakage Current
Due to its narrower bandgap, germanium devices suffer from higher off-state leakage current, reducing efficiency and reliability, especially in low-power electronics.
6. Mechanical and Processing Challenges
Germanium is:
- More brittle than silicon
- More sensitive to thermal stress
- Harder to process consistently in large-scale wafer fabrication
This increases manufacturing complexity and cost.
Why Silicon Dominates Modern Electronics
Because of its thermal stability, low cost, robust oxide layer, and mature manufacturing ecosystem, silicon has become the backbone of the global semiconductor industry. Germanium is now used mainly in specialized applications, such as:
- Infrared optics
- High-speed detectors
- SiGe (silicon–germanium) heterostructures
- Thermal imaging systems
Summary
While germanium offers advantages such as high carrier mobility and excellent infrared performance, its thermal limitations, higher cost, and processing challenges make it less suitable than silicon for mainstream electronics. Silicon remains the dominant semiconductor material, with germanium reserved for niche and high-performance applications.