As we know that conductivity of semicondutors can be increased or

lazyaditya

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
?

davenn

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

Bobbywhy

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/produc...nas-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!

lazyaditya

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.

davenn

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

lazyaditya

ok thnx :)