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Measurement of graphene transport properties
Nečesal, Daniel ; Procházka, Pavel (referee) ; Kormoš, Lukáš (advisor)
In order to create electronic devices utilizing graphene, it is necessary to manu- facture large sheets of high quality graphene which can be achieved by chemical vapor deposition (CVD). Mobility plays an important role in determining quality of graphene sheet because it is inversely proportional to concentration of defects. In this work, CVD graphene samples were fabricated, and their transport properties were characterized by van der Pauw and Hall bar methods. Graphene was transferred to samples either by using Fe(NO3)3 solution or via electrolytic delamination process. Both methods yiel- ded highly p-doped graphene. The electrolytic delamination transfer process resulted in a higher mobility of the graphene sheet and the Dirac point was observed due to a significant doping decrease.
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Influence of electron beam on graphene field effect transistors
Mareček, David ; Čech,, Vladimír (referee) ; Čechal, Jan (advisor)
This diploma thesis deals with electrical conductivity of a graphene sample, preparation of a graphene field-effect transistor and his irradiation by electron beam. In the theoretical part of the thesis, we describe electronic properties of graphene, preparation of graphene by CVD and its transfer to Si substrate with SiO_2 layer. Experimental part of this thesis is focused on the preparation of a graphene field-effect transistor for use in UHV conditions. Futher describes electron beam scanning over the transistor and creation of current maps of tranzistor. In the last part, the thesis deals with influence of electron beam on transport properties of graphene layer and doping of graphene layer by electron beam.
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Preparation of graphene samples for experiments under UHV conditions
Mareček, David ; Mach, Jindřich (referee) ; Čechal, Jan (advisor)
This bachelor thesis deals with electrical conductivity of a graphene sample and preparation of a graphene field-effect transistor. In the theoretical part of the thesis, we describe electronic properties of graphene, preparation of graphene by CVD and its transfer to SiO_2. Experimental part of this thesis is focused on the preparation of a graphene field-effect transistor with long distance between Source and Drain electrodes. Thesis deals with a design of a chip expander for contact of graphene in UHV conditions. The last part describes measurement of dependency of graphene layer conductivity on the gate voltage with emphasis on the position of Dirac point during adjustments of the sample in UHV conditions.
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