briefly
explain how n-types are doped
Doping is
the addition of impurities to an intrinsic semiconductor to increase its
effectiveness. Pentavalent atoms are atoms with five electrons in their
outermost shell, when these atoms are added to a semiconductor like silicon and
germanium with only four valence
electrons in their outermost shell, they
introduce a free electrons which are
ready to move as electric current when a voltage is applied. therefore doping a semiconductor with pentavalent
impurities results in n-type type semiconductor.
state
difference between pentavalent and trivalent impurities
Pentavalent
impurities are atoms that create n-type semiconductor, they are atoms with 5
electrons in their outermost electronic shell. Their excess electrons makes the
semiconductor to have a free unbound electrons . These excess electrons makes the
semiconductor to have negative electrons as majority carriers where as trivalent
element create p-type extrinsic semiconductor,
the impurities “starve” the semiconductor of electrons . They are mostly metals and attract the electrons in semiconductors thereby creating a hole ( empty space) this increase the tendency of the doped
semiconductor to attract electrons and
hence a p-type semiconductor is created.
what
are the major importance of doping in semiconductors
the importance
of doping is to increase the “effectiveness” of the a semiconductor, an intrinsic or pure semiconductor has equal number of negative electrons and positive
holes and their conductivity is rather determined by the thermal agitations or
properties of the materials they found themselves.
therefore dopants increases the conductivity,
if they are pentavalent atoms , they do so by introducing free electrons into
the semiconductor while trivalent atoms
creates an empty vacancy called a hole, thereby making the semiconductor ready
to attract electrons( that is to behave like electronegative atoms)
can
you define p-type and n-type semiconductors
An n-type
semiconductor has an excess of electrons , this made it ready to donate the electrons , it has negative electrons as
it majority charge carrier. The four electrons of the semiconductor will bond
covalently with four of the five
electrons of the pentavalent atoms, the remaining one electron will remain
free. When a voltage is applied the electrons will be “readily” to move as
electric current .
While p-type
semiconductor has hole as majority carriers
the addition of trivalent atoms to a
pure semiconductor will shift the electron to hole concentrations in a semiconductor . Thereby creating a hole
(electrons seeking space) and hence a
p-type is formed
No comments:
Post a Comment