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 |
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 |
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. \(6.7~\text{eV}\)