nl5b02429_si_001.pdf (2.56 MB)
In Situ Observation of Initial Stage in Dielectric Growth and Deposition of Ultrahigh Nucleation Density Dielectric on Two-Dimensional Surfaces
journal contribution
posted on 2015-10-14, 00:00 authored by Jun Hong Park, Hema C.
P. Movva, Evgeniy Chagarov, Kasra Sardashti, Harry Chou, Iljo Kwak, Kai-Ting Hu, Susan
K. Fullerton-Shirey, Pabitra Choudhury, Sanjay K. Banerjee, Andrew C. KummelSeveral
proposed beyond-CMOS devices based on two-dimensional (2D) heterostructures
require the deposition of thin dielectrics between 2D layers. However,
the direct deposition of dielectrics on 2D materials is challenging
due to their inert surface chemistry. To deposit high-quality, thin
dielectrics on 2D materials, a flat lying titanyl phthalocyanine (TiOPc)
monolayer, deposited via the molecular beam epitaxy, was employed
to create a seed layer for atomic layer deposition (ALD) on 2D materials,
and the initial stage of growth was probed using in situ STM. ALD pulses of trimethyl aluminum (TMA) and H2O resulted
in the uniform deposition of AlOx on the
TiOPc/HOPG. The uniformity of the dielectric is consistent with DFT
calculations showing multiple reaction sites are available on the
TiOPc molecule for reaction with TMA. Capacitors prepared with 50
cycles of AlOx on TiOPc/graphene display
a capacitance greater than 1000 nF/cm2, and dual-gated
devices have current densities of 10–7A/cm2 with 40 cycles.
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Dielectric Growthlayer depositionreaction sitesseed layerALD pulsessurface chemistry50 cyclesdielectrictitanyl phthalocyanineInitial StageTiOPc molecule2 D layersTMA40 cyclesH 2Obeam epitaxyUltrahigh Nucleation Density Dielectricuniform depositiontrimethyl aluminumAlOxSitu ObservationDFT calculations2 D materialsSTMdevice
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