Simple excitations like light, heat or small applied voltage can change
the number of mobile charges in a semiconductor Note that the supply
Chapter Fourteen
SEMICONDUCTOR
ELECTRONICS:
MATERIALS, DEVICES
AND SIMPLE CIRCUITS
Rationalised 2023-24
Physics
324
and flow of charge carriers in the semiconductor devices are within the
solid itself, while in the earlier vacuum tubes/valves, the mobile electrons
were obtained from a heated cathode and they were made to flow in an
evacuated space or vacuum No external heating or large evacuated space
is required by the semiconductor devices They are small in size, consume
low power, operate at low voltages and have long life and high reliability