01․ What will happen if doping of an intrinsic semiconductor with pentavalent impurity atom ?
When the donor density is increased, the Fermi level moves closer to the edge of the conduction band.
02․ Silicon has
A semi-conductor has 4 valence electrons. Silicon is semi-conductor. So, the valence electrons of Silicon are 4. Atomic number of silicon is 14. so its configuration is (2 8 4). The last 4 electrons acts as a valance band.
03․ Germanium has
A covalent bond is the chemical bond that involves the sharing of pairs of electrons between atoms. In the electronic configuration of germanium crystals there are four valence electrons. These four electrons will form covalent bonds, with the neighboring electrons of the germanium atoms. Each covalent bond is formed by sharing each electron from the each atom. After bond formation, no free electron will remain in the outermost shell of the germanium semi conductor.
04․ Energy gap of conductor is
Energy gap is the gap between conduction band and valance band. Energy gap Eg of conductor is 0 eV since it has overlapped valance and conduction band.
05․ Energy gap of semiconductor is approx
Energy gap is the gap between conduction band and valance band. Energy gap Eg of the semiconductor is relatively small around 1 eV.
06․ Why is silicon preferred than germanium ?
Silicon is more preferred than germanium while manufacturing the semiconductor devices because of the following reasons:
i. The current sensitivity of silicon with temperature is less than that in germanium.
ii. Silicon has higher tolerance to temperature than germanium.
iii. The leakage current due to minority charge carrier is less in silicon than that in germanium.
07․ Why holes are not created in a metal ?
In a conductor, the forbidden band is missing and the conduction band and valance band are overlapped. Therefore, no holes can be created in a metal.
08․ Which is the pair of acceptor elements ?
When boron or aluminum atoms that have three bonds accept an electron pair from Gallium.
09․ A Semiconductor has a
Negative Temperature coefficient of resistance means, the resistance of the material decrease with increase in temperature. Due to this property semiconductor behave like an insulator at very low temperature but act as a conductor at high temperature.
10․ The most commonly used semiconductor is
The maximum working temperature of Germanium is 75° but silicon can be operated up to 150°. Another reason for choosing silicon is its knee voltage, the knee voltage of silicon is .7 V, whereas the knee voltage of germanium is .3 V.
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