Messages

16

General Questions and Answers / it is the channel too short to make PLDOS of p-i-n junction looks like that

« on: February 20, 2019, 08:52 »

Hi :
recently, i have plot a PLDOS of P-i-N  junction model, and found the pictures look like  that :
i guess it is the too short channel length or too heavily doped on N region or p region? THANKS VERY MUCH IF SOMEONE COULD HELP ME

17

General Questions and Answers / Re: the inelastic current is needed to taken into account if the channel is short

« on: February 19, 2019, 09:59 »

thank you for your reply.
i have a question if i consider EPC effect into my short device. and found the current increase.(maybe it is natural).
but it is unreasonable in physics because the channel is short, the ballistic electron like , it has no chance to exchange energy with phonon in reality.
so i am wondering the inelastic current has really meanful?


thanks very much !

18

General Questions and Answers / Re: the inelastic current is needed to taken into account if the channel is short

« on: February 18, 2019, 10:18 »

 thank you for your reply.
i noted the paper you mentioned in that reference, the PN junction is about the 10 plus nm.
and my current device, the channel is the only 3nm, so may i ask it is necessary to take the EPC account ?

19

General Questions and Answers / the inelastic current is needed to taken into account if the channel is short

« on: February 17, 2019, 14:01 »

Hi all:
I have the question is because as I know in a short channel in devices, i.e under the electron mean free path about 1 um, the electron transport belongs ballistic transport, the electron-phonon coupling can be omitted. is there any necessity to take the inelastic current into account?

if we consider the temperature effect on the transport properties? it is necessary to take the inelastic current into account although the short channel about 1nm?

please help me make this concept clear.
thanks very much?



 

20

General Questions and Answers / a question of python program in the builder console

« on: February 12, 2019, 14:31 »

Hi ;
i want to modify the Y  coordinates of 50  atoms which have a tag，for example "selection atoms",
every atom should be added random delta Y  on its original Y coordinate.
i think it is not wise for me to add the delta Yone by one
so it would be done by making a program in the builder console.
i have three questions:
how 'to extract the 50 atoms Y coordinates in builder console? which function should be used?
and how to generate a random number?
and how to update the modify Y coordinates?
I am very sorry I am a newer python programmer. how to use the builder console, would you please give me some hints?


thanks very much

21

General Questions and Answers / Re: Can ATK analyze TransmissionEigenstate with Noncollinear and SOC

« on: February 10, 2019, 14:23 »

It is not supported in QuantumATK 2018 either.

may i ask the transmisson spectra is support SOC in 2018 version

22

General Questions and Answers / The newest pp pseudodojo pp can support spin orbital coupling

« on: February 9, 2019, 10:29 »

Hi :
i want to see the band split due to the soc,  and i am wondering the pseudoDojo pp can support this kind calculation?

thanks very much

23

General Questions and Answers / some theory backgroud of photocurrent about the indirect gap semiconductor

« on: February 9, 2019, 05:02 »

Dear:
i have a question about the photocurrent model in quantumATK.
If there is an indirect gap semiconductor, its direct gap is A, and indirect gap B , of course, A is bigger than B, so it is an indirect band gap .
so i am wondering in the theoretical framework of quantumATK, the allowed smallest transition energy of an electron from valence to conductance is A or B? i.e the indirect inter-band transition is allowed? because it needs phonon energy because momentum difference .


 

24

General Questions and Answers / is the photocurrent would be applied to two-probe coniguration

« on: February 8, 2019, 11:07 »

HI:
I am looking for the help file about the photocurrent calculation, but there are only for PN-junction, not two-probe configuration,
so I am wondering the photocurrent can be applied to a two-probe configuration?
please give me some hints and help.
thanks very much

25

General Questions and Answers / Re: problems in running the newly added "OptimizeDeviceConfiguration" module

« on: February 7, 2019, 11:13 »

Dear QuantumWise Staff,
   I have been trying to use the new "OptimizeDeviceConfiguration" module for a silicon/MoS2 interface. The programs always got terminated because of something that I cannot follow.
I run the programs in our University clusters, normally I request 4 nodes and 10 processors per node.

The first input file "Device_Si_MoS2_localRun.py" was terminated within 1 min, reporting license problem, which is obviously not true, because another program was running properly.

The second input file "Device_Si_MoS2.py" was terminated after 8 hours, reporting "trace back...", which I cannot follow.
 Attached are the py input files and error and output info. Please help take a look. Thanks a lot.

hi，have you solved the problem?

26

General Questions and Answers / Re: how to calculate the band gap of graphene/mos2 heterostructure correctly

« on: January 25, 2019, 12:29 »

i want to get the correct band gap of graphene/...

Pristine graphene has a zero gap, which is protected by the symmetry of the graphene lattice - two carbon sublattice are equivalent - and that does not depend on the DFT functional you are using.

thank you, indeed prinstine graphene is gap-zero, but the MoS2/Graphene is non-zero small gap as many reference menthoned.

so i think it is depending on the the DFT functioanl useing maybe

27

General Questions and Answers / how to calculate the band gap of graphene/mos2 heterostructure correctly

« on: January 22, 2019, 11:45 »

Hi:
i want to get the correct band gap of graphene/mos2 heterostructure,
one method is to use MGGA, but as the manual said, the c-parameter should test manual because the supercell have big vacuum region, because there are no corresponding bulk graphene/mos2, so the c-parameter can not be determined by known value as the manual said,
so i am wondering how to test the MGGA-c-parameter.
and another question is is there any better to calculate the band gap of such two-dimensional heterostructure in ATK?

THANK YOU VERY MUCH

28

General Questions and Answers / Re: how to analysis the quantum interference based on the transmission pathways

« on: January 17, 2019, 06:04 »

but transmission pathways can only get the direction of current flow between atoms? how the interference can be analyzed   

It depends on what you mean by interference analysis. You might for example look at the Transmission Eigenstates (2D or 3D wave function image), https://docs.quantumwise.com/manual/Types/TransmissionEigenstate/TransmissionEigenstate.html. But it is really up to you to decide on what kind of physical quantities you want to study in the numerical calculations.  We can then advise you if that particular quantity can be computed in QuantumATK.

thank you for your kindly reply,
in fact, i want to know there is a destructive quantum inertereface or not.
i saw some paper, including the paper listed in the website of about transmission pathways, said if there is a ring current, it means there is a destructive. but it is only valid for the ring structures. for the linear structures, how can i know:)

29

General Questions and Answers / how to analysis the quantum interference based on the transmission pathways

« on: January 15, 2019, 07:39 »

Dear all:
I have modeled a molecular electron device, and I want to know is there any interesting quantum interference between molecular and electrode.
as I know the transmission pathways can help it.
but transmission pathways can only get the direction of current flow between atoms? how the interference can be analyzed   

anyone can help me
great appreciated

thank you

30

General Questions and Answers / is the hartree_difference_potential flat?

« on: December 7, 2018, 13:23 »

Hi ATK support:
I tried to plot the Hartree difference potential to check the central region is enough long or not,
the plot is in the attachment.
but I do not know it is flat or not?, because I set the Y axis is from -1 to 1 eV. when I set Y -0.06 to  0.12 eV , it seems not flat.
so my question is how to set Y axis region when I check the length of  central region.