Strain-induced pseudo-magnetic fields in graphene for novel optoelectronic applications

Abstract

The research progress toward creating efficient light sources on graphene-based electronic-photonic integrated circuits has been relatively sluggish, mainly because of graphene’s zero-bandgap nature. Recently, strain-induced pseudo-magnetic fields in graphene have attracted particular interest due to their capability to mimic real magnetic fields and create energy gaps, emerging as a promising route to favor the realization of integrated graphene optoelectronic devices. Theoretical and experimental work on generating strain-induced pseudo-magnetic fields in graphene has been demonstrated. In the meantime, scanning tunneling spectroscopy has repeatedly witnessed the pseudo-Landau levels in strained graphene and verified the existence of pseudo-magnetic fields. However, the effect of pseudo-magnetic fields has been rarely explored in graphene thus far. Moreover, previous attempts to experimentally achieve strain-induced pseudo-magnetic fields have mostly been limited to the nanometer scale, making it challenging to harness them in graphene-based optoelectronic applications. In this thesis, we focus on investigating strain-induced pseudo-magnetic fields in graphene. Starting from fabricating highly strained graphene on nanopillars, we demonstrate how pseudo-magnetic fields change the optical properties of graphene. In the second part, we experimentally induce quasi- uniform pseudo-magnetic fields over an area that can be at the micrometer scale. The demonstrated platform allows customizing the strain distribution in a simple and reproducible way. Using theoretical simulations, we also present the possibility of creating an efficient graphene-based laser. Lastly, I strive to show that graphene holds the potential to act as a light source material by employing ultrafast photoluminescence measurement. Throughout this thesis, we discuss the realization and effect of strain-induced pseudo-magnetic fields in graphene that will help pave the way towards facilitating graphene-based light sources and completing graphene-based electronic-photonic integrated circuits.