Electrical performance enhancement of 20 nm scale graphene nanoribbon field-effect transistors with dipolar molecules

Abstract

Graphene Nanoribbons (GNR) are been being investigated as they possess a bandgap in contrast to graphene sheets which have zero bandgap [1, 2]. Therefore, GNR might be more suitable as a channel material in field-effect transistors (FETs) which requires a high on/off ratio. The other electrical properties of GNR FETs apart from on/off ratio, however, are not as good as those of corresponding graphene sheet FETs. Most GNR FETs have a larger hysteresis, a lower mobility and a larger Dirac voltage than those of graphene sheet FETs. The critical factor that results in degraded performance of GNR FET is edge defects, since GNR due to their geometry have a larger number of edges per active channel width. Moreover, edges of patterned GNR from chemical vapor deposition (CVD) grown graphene do not have a perfect chirality and inevitably have more broken bonds. Thus defect passivation or amelioration assumes considerable importance if the excellent potential of GNR as a semiconducting material is to be realized. In this abstract we report the effect of polar vapors on the electrical characteristics of GNR FET, which is fabricated via patterning from CVD grown graphene monolayer sheet. Our goal is to use these as model studies in designing suitable cap layers that both protect the nanoribbons from the ambient and favorably influence, to a considerable degree, their electrical properties.