Optical properties and carrier transport in graphene-mesoporous silicon nanocomposites

Graphene outstanding properties has been used to enhance the performance of various optoelectronic devices, in particular the field of photovoltaics [1]. In this work, we investigate the optical properties and charge carrier transport of mesoporous silicon nanocomposites coated with few—layer graphene. Photoconductivity properties and carrier capture/recombination dynamics of the photocarriers in these films are studied via optical pump-terahertz probe measurements. Our results show influence of carbon deposition temperature on the Si nanocrystallites luminescence bands as well as the appearance of new higher energy emission bands. The carrier recombination dynamics is largely affected by the presence of defects at the Si/graphene interface. The frequency dependent photoconductivity curves are well reproduced by the Drude-Smith model, like that used for studying the properties of a film composed of Si nanoparticles dispersed in an oxide matrix [2]. The relatively high mobility and low carrier recombination time in these nanostructures make them good candidates for THz photoswitch applications.
[1] T. Mahmoudi, Y. Wang, and Y-B Hahn, Nano Energy, vol. 47, 51-65 (2018).
[2] L. V. Titova, T. L. Cocker, D. G. Cooke, X. Wang, A. Meldrum, and F. Hegmann, Phys. Rev. B. 83, 085403 (2011).