All the texts say that wen a pn junction is forward biased minority carriers injection takes place....say electrons from n type to p type....these minority carriers in this case electrons move thru the p type material by diffusion...at the same time recombinations occur and as a result a hole is accepted from the end of the p side connected to the wire....i am unable to understand this concept of the hole being accepted on recombination....cud someone plz explain

 

Doped semiconductors are odd animals. This is what the Ebook on this site has to say - http://www.allaboutcircuits.com/vol_3/chpt_2/6.html.

If pn junctions don't make you crazy enough, look into selenium rectifiers sometime.

 

yeah the ebook reiterates the same thng widout specifying how...

 

Being a technician, I tend to say "the electrons gotta go somewhere" and go on using diodes, transistors, etc. The mechanism by which holes keep appearing to recombine with electrons is really somewhere beyond wierd.

 

Think about having a fixed number of mobile electrons and an equal number of holes. When an electron moves in one direction it leaves a hole behind. As the electron moves in one direction the holes appear to move in the opposite direction.

 

appreciate ur replying papabravo...but i dont think u quite got wat i was trying to ask...also electron movement doesnt always imply hole movement...

and beenthere this is sumthng tat has been bugging me for quite some time...i guess i will hav to move on...

 

Sorry you feel that way. Maybe you could rephrase the question in a way that the answer would actually be helpful. It did seem as though you were looking for the most elementary explanation possible. Why dress it up with complexities and exceptions if you can't get your arms around the basic physical and chemical properties of materials. You might have a future in Art History.

 

i dont thnk d question needs to be rephrased....still wat i m asking is "wen a junction is forward biased majority carriers of 1 side r injected into the opposite
side wer ther concentration is less.(say electrons from n to p)...these then move thru tat side by diffusion n at same time recombinations occur because of the huge conc diff....each time a recombination occurs say referring to the above example of electrons in p side then simultaneously the external ckt feeds a hole to the p side...y"

n i thought this forum was abt no personal attacks...u dont seem to be no eisntein urself..

 

I don't see a personal attack anywhere. I gave you an answer that I thought would be helpful, you said it wasn't helpful and proceeded to tell me why my answer was not helpful or possibly wrong. OK I can accept that, but you still might want to rephrase your original question because for the life of me I can't figure out what you need.

Also I have never claimed to be Einstein, and I consider your statement a personal attack on me so you might want to practice what you preach.

One last helpful suggestion is to avoid textspeak and IM abreviations. It only serves to obscure and inhibit two way technical communication.