why common emitter amplifier os preferred over common base amplifier?

Name the process responsible for depletion layer formation in p n junction?

Why should the n-Si wafer in solar cell be thin layered?

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Common emitter amplifier is preferred over common base amplifier because in common base amplifier current gain < 1 whereas in common emitter amplifier there is very high current gain.

Due to the difference in carrier concentration in  both sides of the  p-n junction, diffusion of majority charge carriers takes place which causes in the formation of Depletion layer.