CNR ExploRA

Articolo in rivista, 2022, ENG, 10.1088/2053-1583/ac57c9

Mapping the complex refractive index of single layer graphene on semiconductor or polymeric substrates at terahertz frequencies

Pistore V.; Balci O.; Zhang J.; Schinde S.M.; Meersha A.; Ferrari A.C.; Vitiello M.S.

NEST, CNR, Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, 56127, NEST, CNR - Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy, , , , Italy; NEST, CNR, Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, 56127, NEST, CNR - Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy, , , , Italy; NEST, CNR, Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, 56127, NEST, CNR - Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy, , , , Italy; Cambridge Graphene Centre, University of Cambridge, Cambridge, CB3 0FA, Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, United Kingdom, , United Kingdom

Assessing experimentally the main optical parameters of graphene (e.g. complex refractive index, carrier density, mobility) in the far-infrared (0.1-10 THz) is important for quantum science, due to the possibility to devise miniaturized devices (frequency combs, random lasers), components (optical switches, spatial light modulators, metamaterial mirrors and modulators) or photonic circuits, in which graphene can be integrated with existing semiconductor technologies to manipulate their optical properties and induce novel functionalities. Here, we combine time domain terahertz (THz) spectroscopy and Fourier transform infrared spectroscopy to extract the complex refractive index of large ( 1/41cm2) area single layer graphene on thin ( 1/40.1-1 ?m) polymeric suspended substrates, flexible and transparent films, and high reflectivity Si substrates in the 0.4-1.8 THz range. We model our data to extract the relevant optical (refractive index, absorption coefficient, penetration length) electronic (Fermi velocity) and electrical (carrier density, mobility) properties of the different graphene samples.

2D materials 9 (2), pp. 1–9