Nucleation of ALD on Graphene and Transition Metal Dichalcogenide (TMDs)
Two-Dimensional semiconductors offer great opportunity for high performance devices because their naturally chemically and electronically passive surfaces allow carrier confinement in a nearly defect free material. However, the chemically passive surfaces make deposition of sub 5nm gates oxides challenging since the surface are inert and chemical functionalization is likely to change the chemical structure or induce doping. An alternative approach is deposition of 1-2 nanometer Al2Ox particles which molecularly chemisorb and nucleate ALD on inert surfaces without perturbing the electronic structure. Uniform and defect-free Al2O3 films were grown on HOPG and MoS2 by ALD at low temperature (50 oC). Capacitance-voltage measurements of Al2O3 films grown at 50 oC using 50 ALD cycles showed an areal capacitance 1.17 μF/cm2 with very small frequency dispersion on HOPG and MoS2, consistent with the absence of induction cycles and formation of a high quality interface.