LDR theory

[Magnus Danielson]

From: Martin Czech <czech at Micronas.Com>
Subject: LDR theory
Date: Tue, 25 Apr 2000 17:12:43 +0200 (MET DST)

> I tried to read more about it...  Most books simply state that "there
> exist LDRs" period.  I begin to realize that the physics of those compound
> semiconductors along with their doping impurities is far more complicated
> then the Shokley Diode model, therefore few formulas are given...
> CdS seems not to be of any interest. May be things vary a lot and are not
> well defined.
> 
> Therefore I should try to measure the temperature dependance.
> Perhaps a bit more time this week, I'm a bit tired after
> 750km cycling Fr, Sa, So and Mo. I need a rest.

Now, I have avoided this topic... but I opened up my book now and maybe could
give some quick hints...

Devices such as CdS semiconductors experience the photoconductive effect.
You migth have better luck my looking at that subject cause it is more probable
that the schoolbooks tell stories about that. For my own sake I have a full
subchapter about the effect in my semiconductor schoolbook.

Anyway, it is really an effect which deals alot with recombination of electrons
and holes in semiconductors. Naturally wavelength and temperature comes into
play as well as physical material and device geometrics. I think this is just
fundamental semiconductor physics all over again...

BTW. All that cycling isn't good for you, you need to get into the lab, inhale
some sane soldering fumes like the rest of us ;)

Cheers,
Magnus