Anomalous optical response of graphene on hexagonal boron nitride substrates

Abstract

Graphene/hBN heterostructures can be considered as one of the basic building blocks for the next- generation optoelectronics mostly owing to the record-high electron mobilities. However, currently the studies of optical properties of graphene are limited to the standard substrates (SiO2/Si, glass, quartz) despite the growing interest in graphene/hBN heterostructures. This can be attributed to a challenging task of the determination of hBN’s strongly anisotropic dielectric tensor in the total optical response. In this study, we overcome this issue through imaging spectroscopic ellipsometry utilizing simultaneous analysis of hBN’s optical response with and without graphene monolayers. Our technique allowed us to retrieve the optical constants of graphene from graphene/hBN heterostructure in a broad spectral range of 250 - 950 nm. Our results suggest that graphene’s absorption on hBN may exceed the one of graphene on SiO2/Si by about 60%.

Non-Additive Optical Response in Transition Metal Dichalcogenides Heterostructures

“…The use of vdW heterostructures for optical engineering has also been suggested by recent theoretical research [33][34][35][36]. Several studies have also reported that when Gr is included in heterostructures, its intrinsic absorption can grow by up to 60% [37,38]. These results raise the fundamental question of non-additive optical effects in heterostructures (Figure 1a).…”