| Summary: | 碩士 === 東海大學 === 物理學系 === 99 === Graphene is a 2D material with honeycomb lattice. We exfoliated graphene by Scotch tape on 300 nm silicon oxide layer and the substrate is p-type silicon substrate. The number of layers was identified by Raman spectroscopy before make it into graphene devices. To fabricate graphene devices, we used photo-lithography and e-beam lithography to define the shape of pattern, assisted by NSL in NCUE. Then Ti(10nm)/Au(30nm) electrodes was sputtered on samples, and shape the boundary by oxygen plasma etching.
Leakage problem usually appears due to poor quality of oxide layer in our samples and incomplete electrodes. And independent of e-beam writing process and contact of pin. In order to confirm its transport quality, we find out its mobility that computed from electric-field effect and resistivity measurement. Mobility of samples we made is about 8450 cm2V-1s-1 and mean free path is 26.4 nm before annealing in vacuum. After annealing, it shows a significant increasing. Mobility can reach 82600 cm2V-1s-1 and mean free path is 258 nm . Additional discovery is air well dope graphene in p-type, and mobility well decrease rapid. Hysteresis effect appears when expose to air and at high temperature. It refer to the residue of photo resist.
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