Physics : Semiconductor Electronics: Materials, Devices and Simple Circuits

A p-type semiconductor is formed by adding 1 indium atom in to a sample of silicon per 5x10⁻⁷ silicon atoms. If the density of atoms in the sample is 5×10²⁸ atoms/metre³, the number of atoms accepted in per metre³ of silicon is

• 1.0 × 10¹³ atoms/cm³

• 2.5 × 10²⁰ atoms/cm³

• 2.5 × 10²⁵ atoms/cm³

• 1.0 × 10¹⁵ atoms/cm³

The energy gap between the valence band and the conduction band for a material is 6 eV. The material is

• an insulator

• a metal

• an intrinsic semiconductor

• a superconductor

An AC signal of 50 Hz frequency is input of a full wave rectifier using two diodes. The output frequency after full wave rectification is

• 25 Hz

• 50 Hz

• 100 Hz

• 200 Hz

To which logic gate does the truth table given below correspond?

• AND

• OR

• NAND

• XOR

Avalanche breakdown in a p-n junction diode is due to

• shift of fermi level

• widening of forbidden gap

• high impurity concentration

• cummulative effect of conduction band electrons collision

The energy band gap is maximum in

• metals

• superconductors

• insulators

• semiconductors

n-type semiconductor is

• positive charged

• neutral

• negatively charged

• None of the above

If dopping in the P region is high, then N region

• depletion layer will be more towards P

• depletion layer will be more towards N

• depletion layer will remain unchanged

• None of the above

For a triode valve µ = 50, ΔV_g = 0.2 V, then value of ΔV_p is

• 5 V

• 10 V

• 0.2 V

• 50 V

To get an output Y =1 from circuit of figure, the input must be

• A = 0, B = 1, C = 0

• A = 0, B = 0, C = 1

• A = 1, B = 0, C = 0

• A = 1, B = 0, C = 1