Monday, October 21, 2013

Why Silicon is preferred over Germanium for Semiconductor Devices?

 As we all know, both Silicon and Germanium are semiconductor devices. But the present trend is to use Silicon instead of Germanium. What may be the reasons?

  1. At room temperature, Silicon crystal has fewer free electrons than Germanium crystal. This implies that silicon will have much smaller Collector cut off current than Germanium.
  2. The variation of Collector cut off current with temperature is less in Silicon compared to Germanium. 
  3. The structure of Germanium crystals will be destroyed at higher temperature. However, Silicon crystals are not easily damaged by excess heat.
  4. Peak Inverse Voltage ratings of Silicon diodes are greater than Germanium diodes.  
  5. Si is less expensive due to the greater abundance of element. The major raw material for Si wafer fabrication is sand and there is lots of sand available in nature. 

But there is a disadvantage for Silicon over Germanium. 
The potential Barrier of Silicon is more compared to Germanium. 
But if we consider the advantages listed above, we can conclude that Silicon is the best element for the Semiconductor Devices and Applications. 

However,  the  first transistor was made of germanium (Ge). :)