I am trying to determine what effect temparature has on semi conductor diodes. I have read that they have a negative coefficient so they are inversely proportional to to cold /heat. Yet more reading indicates that P.I.V. is directly proportional to temparature. Also what effect does temp have on the burn out point and the voltage barrier (knee)???

 

Hello,

Read this quote:

A characteristic of each pn junction is the negative temperature coefficient of the forward bias.
For silicon diodes, it amounts to approximately -2 mV/K and is constant over a wide temperature range.
This temperature coefficient has the consequence that semiconductor circuits are always temperature sensitive.
This causes problems particularly with analog high-precision circuits (AD converters, reference elements, and so on), which must be circumvented using technical circuiting tricks.
The advantage of the temperature coefficient however is that a diode can also be used as a temperature sensor.

This comes from this page:
http://www.vias.org/encyclopedia/semicond_diode_basics.html

Bertus

 

Some kinds of diodes have positive and some negative temperature coefficient. Refer to the datasheet of each to see what it is.

 

There are no spec sheets for this excercise, that is what is frustrating. If I am reading the question correctly, it is semi conductors (general) & how termperature effects (hot or cold) will affect their burn out point, barrier (knee) and P.I.V.. If what you say is correct, than my answer would read that the diode is directly/inversley proportinate and temp would affect accordingly....

 

There are no spec sheets for this excercise, that is what is frustrating. If I am reading the question correctly, it is semi conductors (general) & how termperature effects (hot or cold) will affect their burn out point, barrier (knee) and P.I.V.. If what you say is correct, than my answer would read that the diode is directly/inversley proportinate and temp would affect accordingly....

Normal p-n diodes and BJTs have negative temperature coefficient.