pn junction basics

[colin]

Hi,
Im looking at the phsysics of pn junctions in particular and im having a
bit of trouble understanding the diferenmce between curent generated by
photoelectric efect and that generated by thermal efect...

well i asume there is a diference anyway ?

i understand a photon gives energy to an electron and this alows it to
become free and creates 2 charge carriers, but is this diferent to when
thermal agitation cuases an electron to become free? or have i mised
something.

thanks
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[nan]

"colin" &lt;no.spam.for.me@ntlworld.com&gt; wrote in message
news:k92xc.236$lK5.88@newsfe3-gui...

Hi,
Im looking at the phsysics of pn junctions in particular and im having
a
bit of trouble understanding the diferenmce between curent generated by
photoelectric efect and that generated by thermal efect...

well i asume there is a diference anyway ?

i understand a photon gives energy to an electron and this alows it to
become free and creates 2 charge carriers, but is this diferent to when
thermal agitation cuases an electron to become free? or have i mised
something.

thanks

I'll give it a shot....

Think about the band gap energy, the Fermi energy.
Every material has a thermal energy (or it would be at absolute zero), and
this plays a part in the formation of the pn junction as equilibrium between
major and minor carriers is reached.
As far as photelectric effects playing a part in the formation of a pn
junction, I am not sure how that plays out.

Try posting this question to sci.eng.semiconductors.
It is a pretty technical question.