Test: Semiconductor Physics - Electronics and Communication Engineering (ECE) MCQ

The intrinsic conductivity for germanium is

The intrinsic conductivity for silicon is

The conductivity of an n-type silicon is a σ = q_n μ_n.
Concentration of electrons,

Using “mass-action law'',

∴ Concentration of holes,

When an electron is accelerated by the potential applied to a semiconductor, the energy gained from the field may then be transferred to an atom when the electron collides with the atom.

Given, I = 1.6 x 10^-6 A
= 1.6 x 10^-6 Coulomb/second
Charge crossing a particular cross-section per second = 1.6 x 10^-6 C Hence, number of electrons crossing a particular cross-section per second

Energy band diagram for semiconductor, metal and insulator are shown below.

Both assertion and reason are individually correct statements. However, the reason for assertion is that due to the applied electric field, and electrostatic force is developed on the electron and the electrons would be accelerated in a direction opposite to the applied electric field and this motion is called directed motion of electron.

The current density is given by 

Given, N_A = 0
Using “charge neutrality equation”, we have:
N_D + P = N_A + n
or, N_D + p = ....(i) 
Using'“Mass-action law”, we have:

Substituting value of p from equation (ii) in equation (i), we have:



Neglecting negative sign, we get:

= free electron density or concentration

The force acting on a charge q placed in a magnetic field B and an electric field E is given by
F = qv x B
The velocity of the hole placed in an electric field is


Now, F - + q E ...(ii) (+q = charge on a hole)
Comparing equations (i) and (ii), the electric field due to the Hall effect will be -400 V/cm in +z direction.