Nucleation and Growth of the HfO2 Dielectric Layer for Graphene-Based Devices

We investigated nucleation and growth characteristics of atomic layer deposition (ALD) HfO2 on exfoliated and chemical vapor deposition (CVD) graphene by using two Hf precursors, tetrakis(dimethylamino)hafnium (TDMAH) and hafnium tetrachloride (HfCl4). Experimental results and theoretical calculations indicate that HfO2 nucleation is more favorable on CVD graphene than on exfoliated graphene due to the existence of defect sites. Also, the TDMAH precursor showed much more unfavorable nucleation and growth than HfCl4 due to different initial adsorption mechanisms, affecting lower leakage currents and breakdown electric field. ALD growth characteristics of HfO2 will be fundamentally and practically significant for realizing the fabrication of graphene-based electronic devices.