Semiconductor Electronic Materials, Devices and Simple Circuits

Which one of the following statements correctly distinguishes an intrinsic semiconductor from an extrinsic semiconductor?

1. Intrinsic semiconductors contain impurity atoms, whereas extrinsic semiconductors are completely pure.
2. Intrinsic semiconductors are pure, whereas extrinsic semiconductors are obtained by controlled doping with impurities.
3. Intrinsic semiconductors conduct only at absolute zero.
4. Extrinsic semiconductors have no free charge carriers.

A NOT gate is also known as:

1. Buffer
2. Inverter
3. Encoder
4. Decoder

The Boolean expression for an OR gate is:

1. Y = A.B
2. Y = A + B
3. Y = A'
4. Y = (A.B)'

Which logic gate gives a HIGH output only when both of its inputs are HIGH?

1. OR gate
2. NOT gate
3. AND gate
4. NOR gate

A half-wave rectifier converts:

1. Direct current into alternating current
2. Alternating current into pulsating direct current using only one half-cycle
3. Alternating current into constant direct current without filtering
4. High voltage into low voltage

Which of the following statements is correct regarding the reverse bias of a p-n junction diode?

1. The depletion region becomes thinner and current increases rapidly.
2. Majority carriers cross the junction easily.
3. The depletion region widens and only a small reverse saturation current flows.
4. The barrier potential becomes zero.

A p-n junction diode is primarily used as:

1. An amplifier
2. A rectifier
3. An oscillator
4. A transformer

A Zener diode is normally operated in:

1. Forward bias below threshold voltage
2. Reverse bias in the breakdown region
3. Forward bias only
4. Reverse bias below breakdown voltage

The barrier potential of a silicon p-n junction diode at room temperature is approximately:

1. 0.1 V
2. 0.3 V
3. 0.7 V
4. 1.5 V

The depletion region in a p-n junction is formed due to:

1. Accumulation of free electrons only
2. Accumulation of free holes only
3. Recombination of electrons and holes near the junction
4. Flow of current through the diode

Which one of the following correctly represents the energy band structure of a conductor?

1. Large forbidden energy gap between valence and conduction bands
2. Small forbidden energy gap of about 1 eV
3. Valence band and conduction band overlap
4. Completely empty valence band

A p-n junction diode conducts significant current when it is:

1. Reverse biased
2. Forward biased
3. Not connected to a battery
4. Connected to alternating current without resistance

In a p-type semiconductor, the majority charge carriers are:

1. Electrons
2. Protons
3. Holes
4. Neutrons

When a small amount of pentavalent impurity is added to pure silicon, the resulting semiconductor is:

1. Intrinsic semiconductor
2. p-type semiconductor
3. n-type semiconductor
4. Insulator

At absolute zero temperature, an intrinsic semiconductor behaves like:

1. A good conductor
2. A superconductor
3. An insulator
4. A semiconductor with maximum conductivity