Why Silicon is preferred in semiconductor?

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Although both silicon & germanium are used in semiconductor devices.
 The present day trend is to use silicon.The main reason for this are:
(1) Smaller ICBO : Silicon have much smaller collector cut off current than germanium. So at room temperature, silicon crystal has fewer free electrons than germanium crystal.
(2) Smaller variation of ICBO with temperature :  The variation of collector cut off current with temperature is less in silicon compared to germanium.
(3) Greater working temperature : The structure of germanium crystals will be destroyed at higher temperature however, silicon crystal are not easily damaged by excess heat.
(4) Higher PIV rating: Peak inverse voltage rating of silicon diode are greater than germanium diode.
(5) Less expensive: Silicon is less expensive due to the greater abundance of element.The major raw material for silicon wafer fabrication is sand & there is lots of sand available in nature.

But there is a disadvantage for silicon over germanium that potential barrier of silicon diode(0.7V) is more compared to germanium diode(0.5). This means higher bias voltage is required to cause current flow in a silicon diode circuit.

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