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Work Function Modulation and Thermal Stability of Reduced Graphene Oxide Gate Electrodes in MOS Devices

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Title Work Function Modulation and Thermal Stability of Reduced Graphene Oxide Gate Electrodes in MOS Devices
 
Creator MISRA, A
KALITA, H
KOTTANTHARAYIL, A
 
Subject graphene
reduced graphene oxide
work function tuning
CMOS
thermal stability
dielectric reliability
Fourier transform infrared spectroscopy
LIGHT-EMITTING-DIODES
CMOS
TRANSPARENT
TRANSISTORS
TECHNOLOGY
PHOTOELECTRON
PHOTOEMISSION
SPECTROSCOPY
RESISTANCE
SILICON
 
Description Work function (WF) tuning of the contact electrodes is a key requirement in several device technologies, including organic photovoltaics (OPVs), organic light-emitting diodes (OLEDs), and complementary metal oxide semiconductor (CMOS) transistors. Here, we demonstrate that the WF of the gate electrode in an MOS structure can be modulated from 4.35 eV (n-type metal) to 5.28 eV (p-type metal) by sandwiching different thicknesses of reduced graphene oxide (rGO) layers between top contact metals and gate dielectric SiO2. The WF of the gate electrode shows strong dependence on the rGO thickness and is seen to be nearly independent of the contact metals used. The observed WF modulation is attributed to the different amounts of oxygen concentrations in different thicknesses of rGO layers. Importantly, this oxygen concentration can also be varied by the reduction extent of the graphene oxide as experimentally demonstrated. The results are verified by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analyses. The obtained WF values are thermally stable up to 800 degrees C. At further high temperatures, diffusion of metal through the rGO sheets is the main cause for WF instability, as confirmed by cross-sectional high-resolution transmission electron microscopy analysis. These findings are not limited to MOS devices, and the WF modulation technique has the potential for applications in other technologies such as OLEDs and OPVs involving graphene as conducting electrodes.
 
Publisher AMER CHEMICAL SOC
 
Date 2014-12-29T05:30:08Z
2014-12-29T05:30:08Z
2014
 
Type Article
 
Identifier ACS APPLIED MATERIALS & INTERFACES, 6(2)786-794
1944-8244
http://dx.doi.org/10.1021/am404649a
http://dspace.library.iitb.ac.in/jspui/handle/100/17197
 
Language English