Enhancing optoelectronic properties of SiC-grown graphene by a surface layer of colloidal quantum dots

摘要

We report a simultaneous increase of carrier concentration, mobility and photoresponsivity whenudSiC-grown graphene is decorated with a surface layer of colloidal PbS quantum dots, which act asudelectron donors. The charge on the ionised dots is spatially correlated with defect charges on theudSiC-graphene interface, thus enhancing both electron carrier density and mobility. This chargecorrelationudmodel is supported by Monte Carlo simulations of electron transport and used to explainudthe unexpected 3-fold increase of mobility with increasing electron density. The enhanced carrierudconcentration and mobility give rise to Shubnikov-de Haas oscillations in the magnetoresistance,udwhich provide an estimate of the electron cyclotron mass in graphene at high densities and Fermiudenergies up to 1.2 × 1013 cm−2 and 400 meV, respectively.