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User defined recombination

Posted Jun 7, 2019, 7:32 a.m. EDT Electromagnetics, Low-Frequency Electromagnetics, Semiconductor Devices 3 Replies

Eray Yurtseven
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I am simulatinig a simple p-n junction and I included a user defined recombination mechanism to my model. And recombination rate is given a constant number (1E26(1/m^3)). However, I observed that calculated current changes with applied bias. How could that be? Is there any specification on applied bias for user defined recombination. I was expecting a fixed current as photocurrent.

3 Replies Last Post Jun 9, 2019, 7:27 p.m. EDT
Dave Greve
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Posted: 6 years ago Jun 7, 2019, 11:13 a.m. EDT
Updated: 6 years ago Jun 7, 2019, 11:13 a.m. EDT

I don't use the semiconductor module but I do know a bit about semiconductors.

Your question doesn't fully make sense. In a photodiode one has an optical generation (not recombination) RATE in units of 1/m^3sec). In the first order theory, the generation rate causes a rigid shift of the I(V) curve to negative currents, resulting in a dependence of current on voltage in forward bias and nearly constant current in reverse bias.

D.W. Greve

I don't use the semiconductor module but I do know a bit about semiconductors. Your question doesn't fully make sense. In a photodiode one has an optical generation (not recombination) RATE in units of 1/m^3sec). In the first order theory, the generation rate causes a rigid shift of the I(V) curve to negative currents, resulting in a dependence of current on voltage in forward bias and nearly constant current in reverse bias. D.W. Greve
Eray Yurtseven
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Posted: 6 years ago Jun 8, 2019, 8:44 a.m. EDT
Updated: 6 years ago Jun 8, 2019, 8:48 a.m. EDT

thanks for unit correction. I just forgot the "sec" term in my explanation.

My question is related with reverse bias case. Order of magnitude difference is available from 0 V to -0.5 V. Is it normal? No SRH, and radiative dark current components, and the temperature is 120 K (low temperature for diffusion dominant trend).

thanks for unit correction. I just forgot the "sec" term in my explanation. My question is related with reverse bias case. Order of magnitude difference is available from 0 V to -0.5 V. Is it normal? No SRH, and radiative dark current components, and the temperature is 120 K (low temperature for diffusion dominant trend).
Dave Greve
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Posted: 6 years ago Jun 9, 2019, 7:27 p.m. EDT
Updated: 6 years ago Jun 9, 2019, 7:24 p.m. EDT

Offhand I can't think of a situation where what you describe would occur.

I would do the following:

  • plot the simulated I(V) for -0.5 < V < 0.5 with and without light
  • calculate the order of magnitude photocurrent using the textbook equations
  • look at plots of electric field and/ or potential through the junction to see if they make sense
  • maybe do it all again at 300 K.

After that and some thinking the explanation and/ or mistake might become clear.

D.W. Greve

Offhand I can't think of a situation where what you describe would occur. I would do the following: - plot the simulated I(V) for -0.5 < V < 0.5 with and without light - calculate the order of magnitude photocurrent using the textbook equations - look at plots of electric field and/ or potential through the junction to see if they make sense - maybe do it all again at 300 K. After that and some thinking the explanation and/ or mistake might become clear. D.W. Greve

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