Practice free NEET NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
For a p-type semiconductor, the acceptor energy level ($E_A$) is located:
The NCERT states, 'for p-type semiconductor, the acceptor energy level $E_A$ is slightly above the top $E_V$ of the valence band as shown in Fig. 14.9(b).'
At room temperature, in an n-type extrinsic semiconductor, what is the predominant source of electrons in the conduction band?
The NCERT text mentions that 'At room temperature, most of the donor atoms get ionised but very few (~10^12) atoms of Si get ionised. So the conduction band will have most electrons coming from the donor impurities...'
In a p-type semiconductor at room temperature, what largely determines the density of holes in the valence band?
The NCERT states, 'At room temperature, most of the acceptor atoms get ionised leaving holes in the valence band. Thus at room temperature the density of holes in the valence band is predominantly due to impurity in the extrinsic semiconductor.'
How does doping influence the intrinsic concentration of minority carriers in an extrinsic semiconductor?
The provided text explains, 'in extrinsic semiconductors, because of the abundance of majority current carriers, the minority carriers produced thermally have more chance of meeting majority carriers and thus getting destroyed. Hence, the dopant, by adding a large number of current carriers of one type, which become the majority carriers, indirectly helps to reduce the intrinsic concentration of minority carriers.'
Which statement correctly describes the overall charge neutrality of extrinsic semiconductors?
The NCERT explicitly states, 'Note that the crystal maintains an overall charge neutrality as the charge of additional charge carriers is just equal and opposite to that of the ionised cores in the lattice.'
In an n-type semiconductor, why can electrons from the donor energy level ($E_D$) move into the conduction band ($E_C$) with a very small supply of energy?
The text states, '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.' This proximity means minimal energy is needed for excitation.
In an n-type semiconductor, at room temperature, which of the following is true regarding the ionisation of donor atoms and intrinsic silicon atoms?
The NCERT text says, 'At room temperature, most of the donor atoms get ionised but very few (~10^12) atoms of Si get ionised.' This clearly indicates that donor atoms ionise predominantly.
In a p-type semiconductor, what is an equivalent description for an electron from the valence band jumping to the acceptor level $E_A$?
The NCERT explains, 'Alternately, we can also say that with very small supply of energy the hole from level $E_A$ sinks down into the valence band. Electrons rise up and holes fall down when they gain external energy.'
For any extrinsic semiconductor at thermal equilibrium, what is the correct relationship between electron concentration ($n_e$), hole concentration ($n_h$), and intrinsic carrier concentration ($n_i$)?
The NCERT states this fundamental relationship: '$n_e n_h = n_i^2$ (14.5)'.
The presence of additional energy states ($E_D$ and $E_A$) in extrinsic semiconductors primarily alters which aspect of their properties?
The NCERT states, 'The semiconductor’s energy band structure is affected by doping. In the case of extrinsic semiconductors, additional energy states due to donor impurities ($E_D$) and acceptor impurities ($E_A$) also exist.' This directly impacts their electrical conductivity.
Ready to ace NEET?
Free access · No credit card required
Yes. You can attempt every NEET question on this page for free without logging in, and check the correct answer with a detailed explanation instantly.
No account is required to attempt questions and view answers. A free account adds bookmarks, personal notes, and progress tracking.
The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.