EASY
Earn 100

What is Fermi Level and Fermi Energy Level.

Important Questions on Semiconductors

MEDIUM
Physics>Modern Physics>Semiconductors>Band Theory of Solids
Explain with the help of a labelled circuit diagram, how an n-p-n transistor can be used as an amplifier in common emitter configuration. Also, explain how input and output voltages are out of phase by180° for a common emitter transistor amplifier.
EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids
In a p-type semiconductor, the concentration of holes is 2×1015 cm-3. The intrinsic carrier concentration is 2×1010 cm-3. The concentration of electrons will be
EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids
Write the truth table of AND gate.
MEDIUM
Physics>Modern Physics>Semiconductors>Band Theory of Solids
In a transistor, IC=0.98, IB=20μA. Find i α and ii β Of the transistor.
EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids
What is the value of energy gap for metals?
EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids
Write two points of advantages of FM broadcasting over AM broadcasting.
HARD
Physics>Modern Physics>Semiconductors>Band Theory of Solids
With reference to semi-conductors answer the following:
i What is the change in the resistance of the semi‐conductor with increase in temperature?
EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids
The band gap in Ge and Si in eV respectively is
EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids
Explain 'Conduction band', 'Valence band' and 'Energy gap' in semiconductors.
EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids
The energy band gap of semiconducting material to produce violet (wavelength =4000Å) LED is _____ eV. (Round off to the nearest integer).
EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids
Write the truth table of two inputs NAND gate.
EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids

State the conditions required to achieve laser action.

 

EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids
Define small signal current gain of a transistor in common emitter configuration.
EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids
Using block diagrams, name the segments of general communication system.
MEDIUM
Physics>Modern Physics>Semiconductors>Band Theory of Solids
For a pure Si crystal has 5×1028 atom $\mathrm{m}^{-3}$. It is doped by 1 PPM concentration of pentavalent As. Calculate the number of electron & holes.
(Given that ni=1.5×1016 m-3 )
EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids
The band gaps of an insulator, conductor and semiconductor are respectively Eg1, Eg2 and Eg3. The relationship between them is given as _____.
EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids
Which of the energy band diagrams shown in the figure corresponds to that of a semiconductor?
MEDIUM
Physics>Modern Physics>Semiconductors>Band Theory of Solids

Match the List I with List II

  List I   List II
A Intrinsic Semiconductor I Fermi-level near valence band
B n-type semiconductor II Fermi-level at middle of valence and conduction band
C p-type semiconductor III Fermi-level near conduction band
D Metals IV Fermi-level inside conduction band

Choose the correct answer from the options given below:

EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids

The chromium ions doped in the ruby rod:

EASY
Physics>Modern Physics>Semiconductors>Band Theory of Solids
Consider a situation in which reverse biased current of a particular P-N junction increases when it is exposed to a light of wavelength ≤621 nm. During this process, enhancement in carrier concentration takes place due to generation of hole-electron pairs. The value of band gap is nearly.