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Robert Zedric

Intrinsic carrier concentration in PADRE appears incorrect

Is there a way to change the value of the intrinsic carrier concentration (ni) in PADRE?  It appears that PADRE uses a value of 5.5 x 109, as opposed to the generally accepted value of 1.5 x 1010 for 300 K. 

I found this by comparing PADRE output data with hand calculations for the majority and minority carrier concentrations in a PN diode.

In the P region of my diode, I use a doping of 1.07 x 1015 of boron.  At equilibrium, this gives a majority carrier concentration of 1.07 x 1015 cm-3 and a minority carrier concentration of n=(1.5 x 1010)2/1.07 x 1015 = 2.1 x 105.  PADRE correctly matches the majority carrier concentration but gives a minority carrier concentration of 2.86 x 104, which is over a factor of 7 off. 

In the N region of my diode, I use a doping of 7.44 x 1013 of phosphorus.  At equilibrium, this gives a majority carrier concentration of 7.44 x 1013 cm-3 and a minority carrier concentration of p=(1.5 x 1010)2/7.44 x 1013 = 3.2 x 106.  PADRE again correctly matches the majority carrier concentration but gives a minority carrier concentration of 4.1 x 105, which is also off by over a factor of 7. 

Using the PADRE minority carrier values and the doping concentrations to back-calculate ni, I find that PADRE uses a value of 5.5 x 109 as the intrinsic carrier concentration at 300 K. 

Please let me know how I can change this value!

Thank you

 

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