01․ The leakage current in a pn junction is in order of
Leakage current flows due to minority carrier in pn junction. So its value is very small in the order of µA.
02․ A pn junction/Diode is a/an
A pn junction / Diode is an unidirectional component. It can conduct only when it is forward biased and act as a close switch, in reverse bias condition it act as a open switch. Forward bias means anode voltage is greater than the cathode voltage.
03․ A semiconductor material is formed by
Semiconductor material are formed by Covalent bonds. It is formed by sharing of four electrons by two atoms, each electron are sharing four other electrons from other atom.
04․ The forbidden energy gap between valance band and conduction band in semiconductor material is about
The forbidden energy gap between valance band and conduction band in a semiconductor devices is arround 1ev whereas in insulator it is 15 ev and in conductor it is 0 ev.
05․ N-type extrinsic semiconductor is obtained by adding
N-type extrinsic semiconductor is obtained by adding pentavalent impurity. Pentavalent impurity has one more extra electron after covalent bond. So pentavalent impurity gives number of free electrons and n type material are obtained.
06․ When Semiconductor materials is heated its resistance
When semiconductor material is heated, electron break away from the atoms and move free from the valance band to the conduction band. So, its conductivity increases and resistivity decreases. As a result resistance decreases.
07․ Which of the following is Pentavalent impurity?
Pentavalent impurity has 5 electrons in valance shell and antimony also have 5 electrons in outer most orbit. So, antimony is a pentavalent impurity. Boron, indium and gallium are trivalent impurity.
08․ The amount of time between the creation and disappearance of a free electrons is called
The amount of time between the creation and disappearance of a free electrons is called life time of the carriers. Life time of the carriers varies from nano-second to several microseconds depending on perfect the crystal is and many other factors.
09․ The majority carrier in P-type extrinsic semiconductor material is
The P-type semiconductor material is obtained by adding trivalent impurity. Trivalent impurity has deficiency of one electron when forming a covalent bond and it creates holes. Trivalent impurity make available positive carriers because they create holes which can accept electrons and thus it the majority carriers are holes.
10․ Conduction electrons have more mobility than holes because they
The mobility of electrons is more than that of holes because the probability of an electron having the energy required to move to an empty state in the conduction band is much greater than the probability of an electron having the energy required to move to the empty state in valance band. The mobility of hole is about half that of electrons.
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