title: In Situ Observation of Initial Stage in Dielectric Growth and Deposition of Ultrahigh Nucleation Density Dielectric on Two-Dimensional Surfaces.
abstract: Several 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/cm(2), and dual-gated devices have current densities of 10(-7)A/cm(2) with 40 cycles.
authors.forename: Jun Hong
authors.initials: JH
authors.lastname: Park
authors.affiliation: Electrical and Computer Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Hema C P
authors.initials: HC
authors.lastname: Movva
authors.forename: Evgeniy
authors.initials: E
authors.lastname: Chagarov
authors.forename: Kasra
authors.initials: K
authors.lastname: Sardashti
authors.affiliation: Electrical and Computer Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Harry
authors.initials: H
authors.lastname: Chou
authors.forename: Iljo
authors.initials: I
authors.lastname: Kwak
authors.forename: Kai-Ting
authors.initials: KT
authors.lastname: Hu
authors.affiliation: Department of Electrical Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States.
authors.forename: Susan K
authors.initials: SK
authors.lastname: Fullerton-Shirey
authors.affiliation: Department of Chemical Engineering, New Mexico Tech , Socorro, New Mexico 87801, United States.
authors.forename: Pabitra
authors.initials: P
authors.lastname: Choudhury
authors.affiliation: Electrical and Computer Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Sanjay K
authors.initials: SK
authors.lastname: Banerjee
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Kummel
keywords: ALD; Dielectric; STM; TiOPc; capacitance; graphene