Tutorial 2 Flashcards
(25 cards)
The periodic table of elements is arranged on the basis of
Atomic number
Which of the following statements concerning the semiconductor doping process is true?
Donors donate electrons
Another name for a trivalent atom
An acceptor
Which of the following statements concerning the semiconductor charge carrier is true?
The conductivity of semiconductors is dominated by their extrinsic carrier concentration.
Can the Fermi level be changed via doping
Yes
True or false , donors introduce an extra level close to Ec
Tru
How do intrinsic semiconductors behave
They have very few charge carriers therefore they behave like insulators
Fermi energy level for semi conductor
Ef=(Ec+Ev)/2
Fermi level for P type semiconductor
Ef
Fermi level for N type semi conductor
Ef>(Ec+Ev)/2
What is the overall charge of a P type semiconductor
Neutral
Define intrinsic semiconductor
Intrinsic semiconductors are the pure semiconductors which have no impurities in them
Define Ev in band theory and describe its band occupancy status at 0 K.
Ev highest possivle valence band energy
The top of the valence band.
Below Ev is completely full (with electrons) at 0K.
Define Eg in Band theory
The energy required to free an electron from a covalent bond.
The energy gap between the top of the valence band and the bottom of the conduction band.
Eg = Ec – Ev
Define Ef in band theory
A state with 50% chance of being occupied by an electron at a given temperature.
At absolute zero no electrons will have enough energy to rise above the Fermi level.
A semiconductor is said to be a ________ type of material
Crystalline
An intrinsic semiconductor does not have
an excess of electrons
an excess of holes
a large number of impurities
Feedback
Conduction in the conduction band of semiconductors is by the movement of
Electrons
Three examples of semiconductors
Gallium arsenide
Germanium
Silicon
Holes are the majority carriers in
A p type semiconductor
Silicon and germanium contain ——- valence electrons
4
True or false, In the quantum model of the atom, an orbital is a discrete energy level where an electron is found.
False
Tru or false, A p-type semiconductor has relatively few free electrons
Tru
Tru or false Hole flow occurs in the conduction band
False
