In molecular Single Electron transistor topics, the island (molecule) does not stay in touch with the dielectric layer physically. It is not clear how the current has been calculated for such SET geometry. can you help me to explain it and give me the reason ?
eg We
setup benzene, anthracene, tetracene and pentacene molecule in the SET geometry as shown in the
Figure 1. It consists of a metallic back-gate, and above the gate there is 3.8 Å of dielectric material
with dielectric constant 10 Є0. The molecule is positioned 1.2 Å above the dielectric. To the left and
the right of the molecule, there are metallic source-drain electrodes respectively. Moreover, the
distance between the molecule and the electrode is kept 2.8 Å.
Why you put the island (molecule) does not stay in touch with the dielectric layer physically. ?
thank you
The molecule is positioned 1.2 Å above the dielectric. ( as indicated in papers below ) the island (molecule) does not stay in touch with the dielectric layer physically.
what is the reason to positioned it with this distance?
Thank you
https://www.researchgate.net/publication/257799351_First-principles_study_of_naphthalene-based_single-electron_transistor?enrichId=rgreq-abbead674e2de22c7bec95d5f2dc64ea-XXX&enrichSource=Y292ZXJQYWdlOzI1Nzc5OTM1MTtBUzoxMDQxMjQyNjM2OTg0NDNAMTQwMTgzNjU2NzkxNg%3D%3D&el=1_x_2&_esc=publicationCoverPdf
http://dx.doi.org/10.1088/0953-8984/28/19/195302
' First-principles modelling of molecular single-electron transistors ' by
Kurt Stokbro
Article First-principles study of naphthalene-based single-electron transistor
To make our device more near to the reality, we have taken into account the existence of van der Waals (vdW) interaction between the molecule and the dielectric surface.
In one special case, polar repulsive are strong enough for them to be exceptionally important in dictating the structure studied. Where oxygen (HFO2) is bonded to an electronegative element. There is a partial negative charge, δ−, on the electronegative element, and an equal and same Cδ- charge such as Carbon. The negatively charged Oδ- can also be repulsed to the partial negative charge on a neighboring molecule (C60). As a result, the molecule/island does not stay in touch with the dielectric layer physically.
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