How Does Wavelength Affect Light Penetration in Photodetectors?

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SUMMARY

The discussion centers on the relationship between wavelength and light penetration in photodetectors, specifically avalanche and p-i-n photodiodes. It is established that longer wavelengths result in greater penetration into the depletion region of these diodes due to lower energy absorption, as described by the equation Eg = hc/λ. The physical significance of wavelength is tied to the energy of light and its interaction with the semiconductor's bandgap, influencing how light is absorbed or transmitted within the material.

PREREQUISITES
  • Understanding of photodetectors, specifically avalanche and p-i-n diodes.
  • Familiarity with the relationship between wavelength and energy (Eg = hc/λ).
  • Knowledge of semiconductor bandgap concepts.
  • Basic grasp of sine and cosine functions and their relevance to wave patterns.
NEXT STEPS
  • Research the absorption characteristics of different semiconductor materials.
  • Explore the impact of wavelength on the efficiency of photodetectors.
  • Learn about the role of the depletion region in photodetector operation.
  • Investigate the applications of infrared light in communication technologies.
USEFUL FOR

Students studying semiconductor physics, engineers working with photodetectors, and researchers interested in the effects of wavelength on light-material interactions.

RajChakrabrty
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Homework Statement



what is the physical significance of wavelength (not the definition)?

Homework Equations



suppose,
in photodetectors (like avalanche or p-i-n photo diodes) incident light having more wavelength,
penetrates more in the diode (particularly in depletion region : )

so, how this more penetration for higher wavelength can be described?

The Attempt at a Solution

 
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How is energy of light related to wavelength? And what is the relation between this energy and the bandgap of the semiconductor?
 
light energy is related to its own wavelength.
Eg=hc/lambda.
lambda=wavelength.

but for more wavelength,
incident light penetrates the photo-detectors more in their depletion region.
my question is how this more penetration for more wavelength can be described,
the physical significance of it.
 
Well penetration means it isn't absorbed. So you have to think of what can cause absorption in a semiconductor and how does this relate to the energy of the light.
 
RajChakrabrty said:

Homework Statement



what is the physical significance of wavelength (not the definition)?
A light wave can be thought of as a repeating pattern of electric and magnetic fields, propagating through space. The wavelength is related to that pattern.
 
Redbelly98 said:
A light wave can be thought of as a repeating pattern of electric and magnetic fields, propagating through space. The wavelength is related to that pattern.

so, what can be realized by wavelength, from this thought?
what is the difference for longer wavelength?
 
Have you been taught about sine and cosine functions in school, and the period of a sine or cosine graph? Those are the concepts that come into play here.

Since this appears to be a homework assignment, we don't just hand out answers. That's why I'm providing conceptual hints to help you think about what is going on.
 
Redbelly98 said:
Have you been taught about sine and cosine functions in school, and the period of a sine or cosine graph? Those are the concepts that come into play here.

Since this appears to be a homework assignment, we don't just hand out answers. That's why I'm providing conceptual hints to help you think about what is going on.
having sine and cosine graph concept and period ...

why light having more wavelength penetrates more?
like why infrared is used for shorter distance than bluetooth?

because of shorter wavelength of infrared.
but,
why short wavelength light is unable to penetrate more?
this is my question, you can say.
 

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