As we know that conductivity of semicondutors can be increased or

In summary, it is said that photoconductivity of the semiconductors is dependent on the wavelength of the light and not on the intensity of the light. This is why many light intensity meters use semiconductors to respond to different wavelengths of light.
  • #1
lazyaditya
176
7
As we know that conductivity of semicondutors can be increased or decreased by supplying heat or photons to the material.

Its said that photoconductivity of the semiconductors is dependent on the wavelength of the light and not on the intensity of the light then how are these used as the light meters
?
 
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  • #2


lazyaditya said:
....Its said that photoconductivity of the semiconductors is dependent on the wavelength of the light and not on the intensity of the light then how are these used as the light meters ?

have you got a reliable reference for that ?

opto semiconductors I have worked with over the years respond nicely to variations in intensity.
you can get the semi to respond to different wavelengths either by the use of a physical filter in front of it or by the actual variations in the manufacture of the semiconductor material to make it more responsive to different wavelengths

cheers
Dave
 
  • #3


lazyaditya said:
As we know that conductivity of semicondutors can be increased or decreased by supplying heat or photons to the material.

Its said that photoconductivity of the semiconductors is dependent on the wavelength of the light and not on the intensity of the light then how are these used as the light meters
?

You can find examples of how different materials respond to different wavelengths here:

"Hamamatsu manufactures various types of infrared detectors made from InSb, InAs, and InAsSb semiconductors. Different materials and types of detector (photodiode, photovoltaic or photoconductive) offer different spectral sensitivity within 1 µm and 6.5 µm."

http://sales.hamamatsu.com/en/produ.../compound-semiconductors/insb-inas-inassb.php

If you check the individual (pdf) data sheets you will see they also respond to the intensity of radiation. Many of them easily function as light intensity meters!
 
  • #4


The thing is i read it in some book ! It was written that the two light of same intensity and different wavelengths will produce different conductivities.
 
  • #5


lazyaditya said:
The thing is i read it in some book ! It was written that the two light of same intensity and different wavelengths will produce different conductivities.

as I hinted at above ... your comment would be correct if the particular semiconductor material used was more sensitive to wavelenght A than it was to wavelength B

Dave
 
  • #6


ok thnx :)
 

1. How can the conductivity of semiconductors be increased?

The conductivity of semiconductors can be increased by adding impurities, also known as doping, to the semiconductor material. This introduces extra free electrons or "holes" into the material, making it easier for electricity to flow.

2. What types of impurities are commonly used for doping semiconductors?

The most commonly used impurities for doping semiconductors are boron, phosphorus, arsenic, and antimony. These impurities have either three or five valence electrons, which creates an imbalance in the semiconductor's crystal structure, leading to an increase in conductivity.

3. Can the conductivity of semiconductors be controlled?

Yes, the conductivity of semiconductors can be controlled by adjusting the amount and type of impurities used for doping. This allows for a range of conductivities, making semiconductors versatile for different electronic applications.

4. How does temperature affect the conductivity of semiconductors?

The conductivity of semiconductors decreases as temperature increases. This is because at higher temperatures, more electrons are able to break free from their atoms and contribute to conductivity. However, at extremely high temperatures, the semiconductor material may become damaged and lose its conductivity.

5. What is the role of band structure in semiconductor conductivity?

The band structure of a semiconductor determines its electrical properties, including its conductivity. In semiconductors, the valence band is completely filled with electrons, while the conduction band is empty. When energy is applied to the material, some electrons from the valence band can jump to the conduction band, creating free charge carriers and increasing conductivity.

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