Damage evaluation in graphene underlying atomic layer deposition dielectrics.

Xiaohui Tang,Nicolas Reckinger,Jean-Pierre Raskin,Jean-François Colomer,Stuart Turner,Benoit Hackens,Pierre Louette,Hosni Idrissi,Damien Cabosart,Olivier Poncelet,Ferran Ureña,Laurent A Francis

doi:10.1038/srep13523

Xiaohui Tang, Nicolas Reckinger + Show 10 more

Open Access

https://doi.org/10.1038/srep13523

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Abstract

Based on micro-Raman spectroscopy (μRS) and X-ray photoelectron spectroscopy (XPS), we study the structural damage incurred in monolayer (1L) and few-layer (FL) graphene subjected to atomic-layer deposition of HfO2 and Al2O3 upon different oxygen plasma power levels. We evaluate the damage level and the influence of the HfO2 thickness on graphene. The results indicate that in the case of Al2O3/graphene, whether 1L or FL graphene is strongly damaged under our process conditions. For the case of HfO2/graphene, μRS analysis clearly shows that FL graphene is less disordered than 1L graphene. In addition, the damage levels in FL graphene decrease with the number of layers. Moreover, the FL graphene damage is inversely proportional to the thickness of HfO2 film. Particularly, the bottom layer of twisted bilayer (t-2L) has the salient features of 1L graphene. Therefore, FL graphene allows for controlling/limiting the degree of defect during the PE-ALD HfO2 of dielectrics and could be a good starting material for building field effect transistors, sensors, touch screens and solar cells. Besides, the formation of Hf-C bonds may favor growing high-quality and uniform-coverage dielectric. HfO2 could be a suitable high-K gate dielectric with a scaling capability down to sub-5-nm for graphene-based transistors.

Highlights

(ALD)[6,7] for dielectric growth on graphene[8]
Based on micro-Raman spectroscopy (μ RS) and X-ray photoelectron spectroscopy (XPS), we study the structural damage induced in 1L graphene underlying HfO2 and Al2O3 upon different oxygen plasma power levels
We have investigated the structural damage in graphene underlying dielectrics (HfO2 and Al2O3) deposited by remote plasma-enhanced ALD (PE-ALD)

Summary

Introduction

(ALD)[6,7] for dielectric growth on graphene[8]. ALD allows for controlling the thickness and uniformity of the deposited films with atomic-level precision while avoiding physical damage of energized atoms to the surface. Various approaches have been proposed: (i) graphene is chemically modified by fluorine[13], ozone[14], nitride plasma[15,16], organic molecules[17] or perylene tetracarboxylic acid[18,19]; (ii) metal particles are deposited on graphene as appropriate nucleation layers[20]; (iii) self-assembled monolayers are used to template the direct growth of dielectrics[21]; (iv) graphene islands, serving as a seed layer, are generated by low-power plasma[22] Some of these approaches are complicated and incompatible with the existing mainstream integrated circuit technology. It could be a good starting material for applications such as graphene-based transistors and sensing devices[26,27], since, presently, wafer-scale homogeneous FL graphene can been synthesized by chemical vapor deposition (CVD)[28]

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