Q. No.A semiconductor is known to have an electron concentration of \(8\times 10^{13}~\text{cm}^{-3},\) and a hole concentration of \(5\times 10^{2}~\text{cm}^{-3}.\) The semiconductor is:
1.
\(\mathrm{n}\text-\)type
2.
\(\mathrm{p}\text-\)type
3.
intrinsic
4.
insulator
Carbon, Silicon, and Germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy gaps represented by \(\left(E_g\right)_C,(E_g)_{Si}~\text{and}~(E_g)_{Ge}\) respectively. Which one of the following relationships is true in their case?
1. \(\left(E_g\right)_C<\left(E_g\right)_{G e} \)
2. \(\left(E_g\right)_C>\left(E_g\right)_{S i} \)
3. \(\left(E_g\right)_C=\left(E_g\right)_{S i} \)
4. \(\left(E_g\right)_C<\left(E_g\right)_{S i}\)
In the given figure, the potential difference between \(A\) and \(B\) is:
| 1. | \(0\) | 2. | \(5\) volt |
| 3. | \(10\) volt | 4. | \(15\) volt |
| 1. | the depletion region becomes thick. |
| 2. | the \(\mathrm{p}\text-\)side is at a higher potential than \(\mathrm{n\text-}\)side. |
| 3. | the current flowing is zero. |
| 4. | the effective resistance is of the order of \(10^6 ~\Omega\). |
If a small amount of aluminium is added to the silicon crystal:
| 1. | its resistance decreases. |
| 2. | it becomes a \(\mathrm{p\text-}\)type semiconductor. |
| 3. | there will be fewer free electrons than holes in the semiconductor. |
| 4. | All of these are correct. |
If in a \(\mathrm{p\text-n}\) junction, a square input signal of \(10\) V is applied as shown, then the output across \(R_L\) will be:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
| 1. | \(\mathrm{n}\text-\)type with electron concentration \(n_{e}=5\times10^{22}~\text{m}^{-3}\) |
| 2. | \(\mathrm{p}\text-\)type with electron concentration \(n_{e}=2.5\times10^{23}~\text{m}^{-3}\) |
| 3. | \(\mathrm{n}\text-\)type with electron concentration \(n_{e}=2.5\times10^{10}~\text{m}^{-3}\) |
| 4. | \(\mathrm{p}\text-\)type with electron concentration \(n_{e}=5\times10^{9}~\text{m}^{-3}\) |
| 1. | the current in the reverse biased condition is generally very small. |
| 2. | the current in the reverse biased condition is small but the forward-biased current is independent of the bias voltage. |
| 3. | the reverse-biased current is strongly dependent on the applied bias voltage. |
| 4. | the forward-biased current is very small in comparison to reverse-biased current. |
| 1. | In the circuit (1) and (2) |
| 2. | In the circuit (2) and (3) |
| 3. | In the circuit (1) and (3) |
| 4. | Only in the circuit (1) |
How much is the forbidden gap (approximately) in the energy bands of germanium at room temperature?
1. \(1.1~\text{eV}\)
2. \(0.1~\text{eV}\)
3. \(0.67~\text{eV}\)
4. \(6.7~\text{eV}\)
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