Enhancing optoelectronic properties of SiC-grown graphene by a surface layer of colloidal quantum dots
journal contributionposted on 27.06.2017, 11:13 by O. Makarovsky, Lyudmila Turyanska, Nobuya Mori, Mark GreenawayMark Greenaway, Laurence Eaves, A. Patane, T.M. Fromhold, Samuel Lara-Avila, Sergey Kubatkin, Rositsa Yakimova
We report a simultaneous increase of carrier concentration, mobility and photoresponsivity when SiC-grown graphene is decorated with a surface layer of colloidal PbS quantum dots, which act as electron donors. The charge on the ionised dots is spatially correlated with defect charges on the SiC-graphene interface, thus enhancing both electron carrier density and mobility. This chargecorrelation model is supported by Monte Carlo simulations of electron transport and used to explain the unexpected 3-fold increase of mobility with increasing electron density. The enhanced carrier concentration and mobility give rise to Shubnikov-de Haas oscillations in the magnetoresistance, which provide an estimate of the electron cyclotron mass in graphene at high densities and Fermi energies up to 1.2 × 1013 cm−2 and 400 meV, respectively.
The work is supported by The Leverhulme Trust (grant number RPG-2013-242), the Engineering and Physical Sciences Council (grant number EP/M012700/1), and the EU Graphene Flagship.