Chapter-14 Semiconductor Electronics: Materials — Online MCQ Test
PHYSICS · CLASS 12 SECOND PUC · Karnataka State Board
Practice Chapter-14 Semiconductor Electronics: Materials with a free chapter-wise online MCQ test.
This chapter covers: Devices and Simple Circuits.
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Chapter-14 Semiconductor Electronics: Materials — Important Questions & Answers
Which of the following is an intrinsic semiconductor?
- A. Pure silicon
- B. Doped germanium
- C. n-type silicon
- D. p-type germanium
Answer: A. Pure silicon
An intrinsic semiconductor is a pure semiconductor material without any doping impurities. Pure silicon is the classic example of an intrinsic semiconductor.
An intrinsic semiconductor is a pure semiconductor material without any doping impurities. Pure silicon is the classic example of an intrinsic semiconductor.
What is the valence electron configuration of silicon?
- A. 3s²3p¹
- B. 3s²3p²
- C. 3s²3p³
- D. 3s²3p⁴
Answer: B. 3s²3p²
Silicon has atomic number 14 with electron configuration [Ne]3s²3p², giving it 4 valence electrons, which makes it a Group 14 element suitable for semiconductor applications.
Silicon has atomic number 14 with electron configuration [Ne]3s²3p², giving it 4 valence electrons, which makes it a Group 14 element suitable for semiconductor applications.
When a pentavalent impurity atom replaces a silicon atom in the crystal lattice, the extra electron becomes a ___.
- A. Hole
- B. Donor level
- C. Free charge carrier
- D. Forbidden band
Answer: C. Free charge carrier
The extra electron from a pentavalent dopant becomes a free charge carrier that contributes to conduction. This electron is loosely bound and easily excited into the conduction band.
The extra electron from a pentavalent dopant becomes a free charge carrier that contributes to conduction. This electron is loosely bound and easily excited into the conduction band.
A semiconductor device operates most efficiently when ___.
- A. Doping concentration is extremely high (>10²⁰ cm⁻³)
- B. The material is perfectly intrinsic with zero doping
- C. Doping concentration is controlled at an optimal level
- D. Temperature is maintained at absolute zero
Answer: C. Doping concentration is controlled at an optimal level
Optimal doping concentration balances charge carrier density and mobility. Too much doping increases scattering and reduces mobility, while too little doping provides insufficient carriers for desired conductivity.
Optimal doping concentration balances charge carrier density and mobility. Too much doping increases scattering and reduces mobility, while too little doping provides insufficient carriers for desired conductivity.
Why are wide band gap semiconductors like GaN and SiC preferred for high-power, high-temperature applications compared to silicon?
- A. They have lower thermal conductivity
- B. They can withstand higher electric fields before breakdown and have lower leakage currents at high temperatures
- C. They are cheaper than silicon
- D. They have higher electron mobility at room temperature
Answer: B. They can withstand higher electric fields before breakdown and have lower leakage currents at high temperatures
Wide band gap semiconductors (GaN: 3.4 eV, SiC: 3.2 eV vs Si: 1.1 eV) can sustain higher electric fields before avalanche breakdown and generate far fewer thermal carriers at elevated temperatures, enabling superior high-power and high-temperature performance.
Wide band gap semiconductors (GaN: 3.4 eV, SiC: 3.2 eV vs Si: 1.1 eV) can sustain higher electric fields before avalanche breakdown and generate far fewer thermal carriers at elevated temperatures, enabling superior high-power and high-temperature performance.