Match List-I with List-II
| List-I (Statement) | List-II (Energy band diagram) |
| (A) An intrinsic semiconductor at \( T = 0\,\mathrm{K} \) | (I)  |
| (B) An intrinsic semiconductor at \( T \gt 0\,\mathrm{K} \) with thermally generated electron-hole pairs. | (II)  |
| (C) Energy bands of n-type semiconductor at \( T \gt 0\,\mathrm{K} \) | (III)  |
| (D) Energy bands of p-type semiconductor at \( T \gt 0\,\mathrm{K} \) | (IV)  |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A)-(III), (B)-(IV), (C)-(I), (D)-(II)
Read each diagram for two things: whether there is an impurity level in the gap, and how many electrons (filled dots) are in the conduction band compared with holes (open circles) in the valence band.
(A) An intrinsic semiconductor at \( T = 0\,\mathrm{K} \) — this matches (III). At 0 K no electron has the energy to cross the gap, so the valence band is completely filled and the conduction band is empty; there are no holes.
(B) An intrinsic semiconductor at \( T \gt 0\,\mathrm{K} \) with thermally generated electron-hole pairs. — this matches (IV). Every electron that jumps to the conduction band leaves one hole behind, so the electrons and holes are equal in number, and there is no impurity level.
(C) Energy bands of n-type semiconductor at \( T \gt 0\,\mathrm{K} \) — this matches (I). The donor level \( E_D \) lies about 0.01 eV below \( E_c \); the donor electrons move easily into the conduction band, so electrons far outnumber holes.
(D) Energy bands of p-type semiconductor at \( T \gt 0\,\mathrm{K} \) — this matches (II). The acceptor level \( E_A \) lies 0.01-0.05 eV above \( E_v \); valence electrons move up into it, so holes far outnumber electrons.
NCERT (2026-27):
Intrinsic Semiconductor – “… An intrinsic semiconductor will behave like an insulator at T = 0 K as shown in Fig. 14.6(a). It is the thermal energy at higher temperatures (T > 0K), which excites some electrons from the valence band to the conduction band. … Here, some electrons are shown in the conduction band. These have come from the valence band leaving equal number of holes there.”
Extrinsic Semiconductor – “… In the energy band diagram of n-type Si semiconductor, the donor energy level ED is slightly below the bottom EC of the conduction band and electrons from this level move into the conduction band with very small supply of energy.”
Extrinsic Semiconductor – “… Similarly, for p-type semiconductor, the acceptor energy level EA is slightly above the top EV of the valence band as shown in Fig. 14.9(b).”