Compound semiconductors

In silicon photonics, why are compound semiconductors combined with silicon for the laser light source?

  1. ABecause silicon does not transmit light at all
  2. BBecause compound semiconductors are always cheaper
  3. CBecause silicon has an indirect band gap and cannot emit light efficiently
Show answer and explanation

Answer: C. Because silicon has an indirect band gap and cannot emit light efficiently

Silicon can be used to make optical waveguides, modulators and photodetectors (combined with germanium), but its indirect band gap prevents it from being an efficient light source. Lasers made of InP-based or other compound semiconductors are therefore bonded to it or combined as separate chips to provide the light source.

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More Compound semiconductors questions

  1. Which trio of researchers received the 2014 Nobel Prize in Physics for inventing the high-brightness blue LED?
  2. Which elements make up gallium arsenide (GaAs)?
  3. Why is LED lighting more energy-efficient than incandescent bulbs?
  4. Which compound semiconductor, with very high electron mobility, is used in magnetic sensors (Hall elements) and the like?
  5. What is the gate structure of the MESFET, long used as a high-frequency GaAs transistor?