Effects of Plasma Treatment on Contact Resistance and Sheet Resistance of Graphene FET
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We investigated the effect of capacitively coupled Ar plasma treatment on contact resistance (Rc) and channel sheet resistance (Rsh) of graphene field effect transistors (FETs), by varying their channel length in the wide range from 200 nm to 50 μm which formed the transfer length method (TLM) patterns. When the Ar plasma treatment was performed on the long channel (10 ~ 50 μm) graphene FETs for 20 s, Rc decreased from 2.4 to 1.15 kΩ·μm. It is understood that this improvement in Rc is attributed to the formation of sp3 bonds and dangling bonds by the plasma. However, when the channel length of the FETs decreased down to 200 nm, the drain current (Id) decreased upon the plasma treatment because of the significant increase of channel Rsh which was attributed to the atomic structural disorder induced by the plasma across the transfer length at the edge of the channel region. This study suggests a practical guideline to reduce Rc using various plasma treatments for the Rc sensitive graphene and other 2D material devices, where Rc is traded off with Rsh.
Abstract
We investigated the effect of capacitively coupled Ar plasma treatment on contact resistance (Rc) and channel sheet resistance (Rsh) of graphene field effect transistors (FETs), by varying their channel length in the wide range from 200 nm to 50 μm which formed the transfer length method (TLM) patterns. When the Ar plasma treatment was performed on the long channel (10 ~ 50 μm) graphene FETs for 20 s, Rc decreased from 2.4 to 1.15 kΩ·μm. It is understood that this improvement in Rc is attributed to the formation of sp3 bonds and dangling bonds by the plasma. However, when the channel length of the FETs decreased down to 200 nm, the drain current (Id) decreased upon the plasma treatment because of the significant increase of channel Rsh which was attributed to the atomic structural disorder induced by the plasma across the transfer length at the edge of the channel region. This study suggests a practical guideline to reduce Rc using various plasma treatments for the Rc sensitive graphene and other 2D material devices, where Rc is traded off with Rsh.
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