High-Velocity Saturation in Graphene Encapsulated by Hexagonal Boron Nitride.
basic_science · Level V
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- Record sourced from PubMed, PMID 28880529.
- Also identified by DOI 10.1021/acsnano.7b03878.
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Abstract
We measure drift velocity in monolayer graphene encapsulated by hexagonal boron nitride (hBN), probing its dependence on carrier density and temperature. Due to the high mobility (>5 × 10<sup>4</sup> cm<sup>2</sup>/V/s) of our samples, the drift velocity begins to saturate at low electric fields (∼0.1 V/μm) at room temperature. Comparing results to a canonical drift velocity model, we extract room-temperature electron saturation velocities ranging from 6 × 10<sup>7</sup> cm/s at a low carrier density of 8 × 10<sup>11</sup> cm<sup>-2</sup> to 2.7 × 10<sup>7</sup> cm/s at a higher density of 4.4 × 10<sup>12</sup> cm<sup>-2</sup>. Such drift velocities are much higher than those in silicon (∼10<sup>7</sup> cm/s) and in graphene on SiO<sub>2</sub>, likely due to reduced carrier scattering with surface optical phonons whose energy in hBN (>100 meV) is higher than that in other substrates.