Chemical vapor deposited graphene for quantum Hall resistance standards

Franz Ahlers, Michel Calame, Kishan Thodkar, Christian Schönenberger
2017 unpublished
Bibliography 122 A Fabrication 135 B CVD graphene growth, transfer and solvent treatment 139 C Setup details and further graphene characterization 143 D Further measurements of LG graphene samples 163 E Molecular modeling of adsorbates on graphene F Collaborations 183 Curriculum Vitae 185 Publications Acknowledgements 190 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
more » ... or 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. The outline of this work is as follows. In chapter 2, a brief background into graphene's properties is described. This is followed with the basic introduction on classical Hall effect and integer quantum Hall effect in graphene. The need for quantum Hall resistance standards (QHR) is presented with a particular focus on the advantage of CVD graphene based QHR. A few details about the cost of graphene production and its application in Hall sensing is presented. In chapter 3, CVD of graphene on copper foils is discussed and various growth recipes demonstrating the control over the size of graphene grains and growth dynamics are presented. Crystallinity of a material defines the purity and ultimately influences its performance. In CVD graphene, the grain boundaries in the film introduce charge scattering and limit the material's performance. However, the occurrence of the grain boundaries can be controlled by altering the growth conditions. It is desirable to have CVD graphene films with large grain size or a uniform mono-crystalline film. These details along with the graphene transfer techniques onto SiO 2 /Si substrate are presented. The limitation of PMMA-assisted transfer and the prime cause behind the presence of polymer residues is highlighted. A thorough characterization of graphene is necessary to understand its limitations and easier integration of new 2D materials with existing CMOS technology. In chapter 4, we describe three distinct tools used to characterize graphene films
doi:10.5451/unibas-006766426 fatcat:re2hebetvrgxpfwzea5in3vsje