N-type and P-type

[Dr. MohammadMahdi Ariannejad]

Dear all;
would you please help me to know how to define the P-type and N-type silicon in optibpm?
I have a wave guide that has P-type part and N-type part, the very sad story is P-type and N-type refractive index in the same of the silicon, so how the software could distinguish which one is P-type or N-type?
I need the answer as soon as we can my friends.
many thanks

[Ravil]

Hi Mohammad,

Just trying to give you a hint and exactly understand your question. What optical properties of your designed material will be different (I mean for N- and P-type) waveguides? How do you specify them in your model?

[Dr. MohammadMahdi Ariannejad]

it is simple, but to me not simple, we have mach zehnder my friend, and one arm is sensing arm right? then this sensing arm that I am studying about suppose to have P and N junction, then we have electrode, this electrode and P-N junction would interfere the light, any idea how to design? still stuck…

[Ravil]

Yes, you are right about your first statement: one arm of Mach Zehnder is usually used for sensing. The first general idea that comes to me is that you can perform modulation by changing electric field with the respect of built-in voltage (and I am pretty sure that what you are doing). The main concept is the same as for regular MZM: the change in electric field should affect the change of refractive index.

[Ravil]

Coming back to your question about the refractive indices for P- and N-type: they should be different since there are different resonance frequencies for these doppings. In my opinion, that is the main point here. Did you consider to assign these indices manually or did you find a proof from the literature that they are equal (can you share the reference in this case)?

[Dr. MohammadMahdi Ariannejad]

Dear Ravil;
“they should be different since there are different resonance frequencies for these doppings.”
I had the same Idea because we can define Rv or optical things inside the software but do you have any idea where I can find the silicon doped properties? I wish it was like the circuit design that each element has datasheet but for us no datasheet!!!!
If you know how to find please let me know
still I am in the stage of reading for this prject I do not have a good references
my main problem now is the designing the electorde of PiN junction and P-N junction in silicon waveguide, searching every paper and journal to find out how to design and which thickness which material and what distance as well, if you have any experiance would you please share? many thanks.

[Steve Dods]

“they should be different since there are different resonance frequencies for these dopings.”
Really? I thought the doping affected the Fermi Level, not the band structure. Electrical properties are influenced by the Fermi Level, but the refractive index is influenced by the band gap energy level. Since the band structure has not been changed by doping, the band gap is the same and the refractive index should also be the same. I suppose if the doping was very high and the Fermi Level became very close to the band edge then the probability of transition could be affected, influencing the refractive index. However, the Fermi level is chosen to make the carriers a minority. So the level must not be too close to the band edge.

[Dr. MohammadMahdi Ariannejad]

Dear Steve, Finally for my problem what you offer me to do and how to define the high doped P or N-type silicon or medium Doped in BPM, still waiting for the answer, we have bunch of software also they are useless in such a case, I was designing in silvaco as well, silvaco is nice however learning is disaster specially about optical, but it does not show me the changes of reflective index regarding to optoelectronic, here we have the optoelectronic module but I think we cannot define doping and electrode potential and so many parameters about electrode, would you please help me if I am wrong any example any data or any paper regarding to this matter can save my life, I wish to do my simulation with BPM and finish it, many thanks.

[Steve Dods]

I don’t think that the doping levels that are used to make p and n materials will change the refractive index of the material significantly. The reason I have stated above.

[Dr. MohammadMahdi Ariannejad]

still unable to simulate the P and N diffusion! is there any update for BPM? wish solve this problem sooner many thanks, any help to find a solution meanwhile?

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