posted on 2021-06-08, 15:33authored bySupriya Ghosh, Hwanhui Yun, Prashant Kumar, Sabrina Conrad, Michael Tsapatsis, K. Andre Mkhoyan
Metal–organic frameworks (MOFs)
are gaining more prominence
as low-dielectric materials for applications in electronic devices
and sensors using top–down electron-beam patterning. Using
a combination of electron diffraction and electron energy-loss spectroscopy
(EELS) in a transmission electron microscope, the details of structural
modification of ZIF-L MOF under electron-beam irradiation were identified.
It was found that the modification of ZIF-L under the electron beam
happens in two distinct stages. In addition to the collapse of the
original ZIF-L porous framework and loss of crystallinity occurring
at the initial low-dose stage, it was observed that the disordered
ZIF-L then undergoes a second stage of changes, where the molecular
structure of the linker starts to breakdown. Further, it was observed
that the degradation of the linker molecules in the second stage of
the ZIF-L modification has a considerable impact on its dielectric
function, shifting energies of the electronic transitions.