Semiconductors and Electronic Devices MCQ Questions & Answers in Modern Physics | Physics

Barrier potential depends on all the three options given. Barrier potential depends on the material used to make $$p$$ - $$n$$ junction diode (whether it is $$Si$$ or $$Ge$$ ). It also depends on amount of doping due to which the number of majority carriers will change. It also depends on temperature due to which the number of minority carriers will change.

Input resistance
$${R_{{\text{in}}}} = \frac{{\Delta {V_{BE}}}}{{\Delta {i_B}}} = \frac{{0.04}}{{40 \times {{10}^{ - 6}}}} = 1k\Omega $$

For using transistor as a switch, it is used in cut-off state and saturation state only..

As in reverse bias, the current through the 0000 is zero through the electric field is also zero.

Output of the given circuit is given by
$$y = \overline {\left( {AB} \right)\left( C \right)} $$
When, $$A = B = C = 0,{Y_1} = \overline {\left( 0 \right)\left( 0 \right)\left( 0 \right)} = \overline 0 = 1$$
When, $$A = B = C = 1,{Y_2} = \overline {\left( 1 \right)\left( 1 \right)} = 0$$

When a small amount of pentavalent impurity is added to a pure semiconductor, it is known as $$n$$-type semiconductor. Phosphorus $$\left( P \right)$$  is a pentavalent and silicon is a tetravalent. Therefore, when phosphotus is doped with $$Si,$$  it forms a $$n$$-type semiconductor.

At the zener breakdown voltage the electric field of the junction is high $$\left( {{{10}^6}\,V/m} \right)$$   enough to pull valence electrons from the host atoms. The emission of electrons from the host atoms accounts for high current at the breakdown.

For forward bias, $$p$$-side must be at higher potential than $$n$$-side.
$$\Delta V = \left( + \right)Ve$$

Silicon is cheaper than germanium, so it is preferred over germanium. But energy gap in germanium is smaller than silicon.

Resistivity of a metal is directly proportional to temperature because its temperature cofficient is positive and resistivity of semiconductor is inversely proportional to temperature. due to its negative temperature coefficient. This implies that with decrease in temperature, resistivity of metal decreases while that of semiconductor increases.
Here, $$Si$$ is a semiconductor and $$Cu$$ is a metal. So, resistivity of $$Si$$ increases but that of $$Cu$$ decreases.