LDR theory

[Ian Fritz]

Magnus --

I think Martin is probably close to the truth here. The wide-gap compounds
are likely to have significant effects due to deep level traps, and since
the devices are polycrystalline there should also be important
grain-boundary effects.

  Ian

----- Original Message -----
From: "Magnus Danielson" <cfmd at swipnet.se>
To: <czech at Micronas.Com>
Cc: <synth-diy at node12b53.a2000.nl>
Sent: Tuesday, April 25, 2000 6:12 PM
Subject: Re: LDR theory


> 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
>