Chapter No. 1. Semiconductor Diode.
Points to remember…..
(i). Valence bond:- Outermost (highest) band filled with electrons & represents the valency of an atom.
(ii). Conduction bond:- Next highest band to valence band contains free electrons for conduction.
(iii). Covalent bond:-These bonds are formed due to sharing of electrons.
(iv). Doping:-Adding impurities to semiconductor& increases the conductivity of semiconductor.
(v). Forbidden gap:- It separates conduction & valence band. No electrons can normally exist in this
Q(1). Explain or Define Conductor?.
(i). Conductors are the substances or materials which allows the electric current to pass through them.
(ii). There is no ‘forbidden gap ’is present between valence band &conduction band. (iii). Hence it
contains larger number of free electrons in conduction band.(iv). In this conductivity is very high &
resistivity is very low.(v). In case of conductors, conductivity is directly proportional to the temperature.
e.g. copper, gold, silver, iron, aluminum, water, graphite etc.
Q(2). Explain or Define Insulator?.
(i). Insulators are the substances or materials which does not allows the electric current to pass through
them. (ii). There is large ‘forbidden gap’ is present between valence band & conduction band.
(iii). Hence it contains small or even zero number of free electrons.(iv). In this conductivity is very low &
resistivity is very high.
e.g. rubber, plastic, wood, glass, paper etc.
Q(3). Explain or Define Semiconductor?.
(i). These are the substances or materials which can acts as a conductor as well as an insulator.
(ii). A semiconductor material is one whose electrical properties lies in between those of insulators and
conductors. (iii). In semiconductors ‘forbidden gap’ is very small.(iv). The conductivity of the
semiconductor increases as temperature increases.(v). Hence as temperature increases electrical
resistance of the semiconductor decreases.
e.g. Germanium (Ge), Silicon (Si), Selenium (Se), Carbon (C) etc.
Classification of semiconductors:-
* Basic Electronics Notes By Er. Swapnil V. Kaware (email@example.com)*