Physics

Semiconductors and Diodes

461 Questions

Semiconductors and diodes form the foundation of modern electronics, covering topics like intrinsic carrier concentration and Zener breakdown. Questions often explore the characteristics of bipolar junction transistors (BJT) and the properties of doped silicon materials. This topic is crucial for physics and electronics engineering competitive exams.

Zener diode breakdownBJT circuit analysisIntrinsic carrier concentrationDoping in semiconductorsEmitter follower circuit

Semiconductors and Diodes Questions

Multiple choice

EPROM consist of

  1. bipolar transistors

  2. mosfets

  3. ujts

  4. diodes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

EPROM (Erasable Programmable Read-Only Memory) is built using MOSFET technology with floating gates. The floating gate can trap charge to store data even without power. UV light erases the charge. Bipolar transistors, UJTs (Unijunction Transistors), and diodes are not used in EPROM manufacturing - MOSFETs are essential for the floating gate mechanism.

Multiple choice

Which of the following helps in reducing the dynatron effect?

  1. Static dischargers

  2. A suppressor grid

  3. A tunnel junction

  4. ISFET
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A suppressor grid is a grid used in a thermionic valve (also called vacuum tube) to suppress secondary emission. A suppressor grid is also called the antidynatron grid, as it helps to reduce the dynatron effect.

Multiple choice

A Fourth Generation chip contains

  1. a single transistor.

  2. less than 100 transistors.

  3. thousands of transistors.

  4. billions of transistors.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Fourth-generation computers are characterized by the use of Very Large Scale Integration (VLSI) technology, which allows thousands of transistors to be placed on a single chip.

Multiple choice

The resistivity of an intrinsic semiconductor decreases with increasing temperature. This is because with increasing temperature,

  1. Both the carrier concentration and mobility of carriers decrease

  2. The carrier concentration increases but the mobility of carriers decreases

  3. The carrier concentration decreases but the mobility of carriers increases

  4. The carrier concentration remains the same but the mobility of carriers decreases

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Conductivity is inversely proportional to resistivity. As we increase the temperature in intrinsic semiconductor, both electrons and holes start vibrating and colliding with each other generating more and more electrons and holes. Due to collision between the atoms, mobility decreases.

Multiple choice

The depletion region of a p-n junction has

  1. Electrons and holes

  2. Positive ions and electrons

  3. Positive ions and negative ions

  4. No ions, electrons or holes

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Only immobile ions form the depletion region in a p-n junction after recommbination. 

Multiple choice

When the reverse voltage across a p-n junction is gradually decreased, the depletion region

  1. Does not change in width

  2. Initially increases up to a certain width and then decreases

  3. Continuously increases in width

  4. Continuously decreases in width

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Depletion width is inversely proportional to reverse bias. Therefore, when the reverse voltage decreases, the width of the depletion layer will increase.

Multiple choice

In an unbiased p-n junction, the junction current at equilibrium is

  1. Due to the diffusion of minority carriers only

  2. Due to the diffusion of majority carriers only

  3. Zero because equal and opposite drift and diffusion currents for electrons and holes cross the junction

  4. Zero because no charge crosses the junction

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

During the formation of p-n junction, before coming to equilibrium, both diffusion and drift current flows attain equilibrium. Hence, there is no current.