Why
Silicon is Preferred over Germanium ?
However silicon is mostly preferred as semiconductor as
compared to germanium due to following reasons.
- The atomic number of germanium is 32
therefore the number of electrons in the first orbit is 2, second orbit is 8,
third orbit is 18 and fourth or last is orbit 4.
- The atomic number of silicon
is 14 therefore the number of electrons in the first orbit is 2, second orbit
is 8 and third or last orbit is 4.
- Therefore the germanium material has valanceelectrons are at higher energy level ( fourth orbit ) as compared to silicon
material ( third orbit ).
- It means that germanium material requires some
additional energy to free electrons from last orbit. This property makes
germanium unstable at higher temperature.
- The working temperature of the germanium is approx 700C
whereas it is 1500C for the silicon.
- The variation of the collector leakage current with temperature
in the germanium is more than that of silicon.
- At room temperature, the collector leakage current in the
silicon is much smaller than that of germanium.
- The
collector leakage current in the germanium material is approx. 10 to 100 times greater than that of
silicon type material.
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