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Why did silicon become the preferred semiconductor material for transistors?
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transistor
NMOS transistor
Negative-channel metal-oxide semiconductors (NMOS) employ a positive secondary voltage to switch a shallow layer of p-type semiconductor material below the gate into n-type. For positive-channel metal-oxide semiconductors (PMOS), all these polarities are reversed. NMOS transistors are more expensive, but faster, than PMOS transistors.
Silicon became the preferred semiconductor material for transistors and integrated circuits primarily because it offered significant performance and manufacturing advantages over germanium, which was the dominant material in the early 1950s.12
The shift to silicon was driven by several key factors:
- Lower Leakage Currents: Silicon devices exhibit much lower leakage currents than germanium devices, which suffered from high leakage at only moderately elevated temperatures.13
- Thermal Stability: Silicon retains its semiconducting properties at higher temperatures, allowing silicon diodes to operate up to 200 °C (400 °F), compared to the 85 °C (185 °F) limit for germanium.2
- Native Oxide Layer: A crucial advantage is that silicon forms a stable, high-quality silicon dioxide (SiO₂) film when heated in oxygen. This insulating layer acts as a mask during manufacturing, protecting the surface and allowing for the precise introduction of impurities to create complex electronic components.123
- Abundance and Cost: Silicon is significantly more abundant in nature than germanium, making it a more cost-effective raw material for large-scale production.2