[DFTB-Plus-User] R: 2 questions regarding transport: heterostructures and scattering

Alessandro Pecchia pecchia at ing.uniroma2.it
Thu Dec 20 13:01:12 CET 2012


Dear Yasin,

just a remark about scattering in transport. 

Surface roughness and impurity will be included only if you make realistic
structures, explicitly containing roughness and impurity atoms. 
We do not have effective 'self-energies' to treat these problems.

Simulating interface roughness in hetero-structures may turn out
computationally expensive as you will need a large supercell in the lateral
directions. 
In this way you can simulate short-correlations, but long correlation
roughness will then require very large cells.
Consider that G.F. scales as M^3,  where M is the number of cross-section
atoms.

Best,

Alessandro.



-----Messaggio originale-----
Da: dftb-plus-user-bounces at dftb-plus.info
[mailto:dftb-plus-user-bounces at dftb-plus.info] Per conto di Gabriele Penazzi
Inviato: giovedì 20 dicembre 2012 11.57
A: dftb-plus-user at dftb-plus.info
Oggetto: Re: [DFTB-Plus-User] 2 questions regarding transport:
heterostructures and scattering

Dear Yasin,

there's no constrain in the DFTB+NEGF code which would prevent you from 
doing that, however I'm not aware of any parametrization which include 
this class of materials. If there's any, than you can use it for 
transport calculation as well.

Phonon scattering is not included in the distributed version, it's under 
development.

Phase-conserving scattering can be calculated, therefore you can 
simulate impurities assuming that you've the right parametrization for 
that and you can definitely calculate surface roughness scattering.

Best,

Gabriele



On 12/19/2012 07:35 AM, Yasin Khatami wrote:
> Hello,
>
> I'm wondering if the heterostructures are supported in DFTB+ NEGF. For 
> example can I simulate a InAs/InGaAs or InAs/Si structure?
> Also is there a way to include phonon scattering and other types of 
> scattering such as surface roughness and impurity scattering?
>
>
> Thanks,
> Yasin
> _______________________________________________
> DFTB-Plus-User mailing list
> DFTB-Plus-User at dftb-plus.info
> http://www.dftb-plus.info/mailman/listinfo/dftb-plus-user


-- 
Dr. Gabriele Penazzi
BCCMS - University of Bremen

http://www.bccms.uni-bremen.de/
http://sites.google.com/site/gabrielepenazzi/

phone: +49 (0) 421 218 62337
fax: +49 (0) 421 218 62770

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