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Dalia Selim Louis

Coupled Mode Space

Dear Sir,

The results obtained using the 2 transport models supported in the tool gives exactly the same results for different nanowire diameters and i noticed that when choosing the coupled mode space transport model, i found that the transport model is Uncoupled in the log file …..any explanation for this please

Thanks in advance

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    SungGeun Kim

    Coupled mode and uncoupled mode space approach can give the same results in ballistic simulations. Please refer to J. Wang’s paper: http://arxiv.org/ftp/cond-mat/papers/0403/0403739.pdf.

    They can be different when you include scattering which I think you cannot do in the tool now. Please see the reference: http://arxiv.org/ftp/cond-mat/papers/0502/0502538.pdf

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    Hong-Hyun Park

    If the material you choose is a direct bandgap semiconductor like GaAs, then the effective masses and the results keep the same regardless of crystal orientations. Also, for Si all equivalent crystal directions such as 100, 010, 001 will give the same results. Please note that the simulation is based on the effective mass approximation. The only thing affected by the crystal orientation is the effective masses (m*_x, m*_y, and m*_z).

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      Dalia Selim Louis

      I am not asking about the crystal orientation….Maybe i was not clear in my question, I was asking about the difference in simulation between the two transport models(Coupled Mode Space and Uncoupled mode space). when i tried to simulate the same nanowire with the same dimensions and material (Si with crystal orientation 100) one time using coupled mode space and the othe other using Uncoupled mode space, I got exactly the same results (I am using large diameter where the coupling between the modes is assumed to be significant).I need an explanation for this please. Another thing please, in the log file during simulation, I have noticed that the transport written is the uncoupled regardless of what was chosen before. Thannks in advance

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        Hong-Hyun Park

        Let me check whether the coupled mode-space approach becomes active when the option is chosen. Maybe the interface between the input deck and simulation engine it not linked correctly. In general, the coupled- and uncoupled-mode space approahes give the same results only when couplings bewtween neighboring slabs is almost unity.

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