Mobility and Saturation Velocity in Graphene on Silicon Dioxide

graphene;mobility;high-field

Dorgan, Vincent E. ; Pop ; Eric

关键词: graphene;    mobility;    high-field;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/16801/Dorgan_Vincent.pdf?sequence=2&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Transport properties of exfoliated graphene samples on SiO2 are examined from four-probe electrical measurements combined with electrical and thermal modeling. Data are analyzed with practical models including gated carriers, thermal generation, “puddle” charge, and Joule heating. Graphene mobility is characterized as a function of carrier density at temperatures from 300 to 500 K. In addition, electron drift velocity is obtained at high electric fields up to 2 V/μm, at both 80 K and 300 K. Mobility displays a peak vs. carrier density and decreases with rising temperature above 300 K. The drift velocity approaches saturation at fields >1 V/μm, shows an inverse dependence on carrier density (~n^-1/2), and decreases slightly with temperature. Saturation velocity is >3×10^7 cm/s at low carrier density, and remains greater than in Si up to 1.2×10^13 cm^-2 density. Transport appears primarily limited by the SiO2 substrate, but results suggest intrinsic graphene saturation velocity could be more than twice that observed here.