Chemical vapor deposited graphene for quantum Hall resistance standards

Abstract

In this PhD project, we address the different aspects in the development of CVD graphene based quantum Hall resistance standards (QHR) for metrological applications. An interesting application of graphene is its use in developing quantum Hall resistance standards (QHR). Resistors are one of the most widely used passive components in electrical circuits, a precise and reliable resistance standard is thus vital for the appropriate calibration and reproducibility of various electronic systems during manufacturing. Standard wire-wound resistors suffer from degradation and at best offer an uncertainty of few parts per million (ppm). The quantized Hall resistance plateaus were recognized to serve as the ultimate reference for resistance standards. The quantized Hall resistances is defined in terms of Planck constant h and electron charge e and are independent of sample dimensions. These advantages along with the universality and robustness of the quantum Hall effect offers an unparalleled advantage over passive resistor standards. Graphene offers a unique advantage in realization of a convenient resistance standard, operating at easier measurement conditions. Low dissipation QHE in CVD graphene has been elusive due to several reasons. The various aspects considered within this project involve the synthesis of large area CVD graphene films on copper foil and its thorough characterization using electrical transport, Raman spectroscopy, X-ray photoelectron spectroscopy and low-energy-electron microscopy. As a highlight, we were able to demonstrate high precision resistance quantization in CVD graphene with an accuracy within 30 parts per billion.