Opening the band gap of graphene through silicon doping for improved performance of graphene/GaAs heterojunction solar cells

摘要

Graphene has attracted increasing interests due to its remarkable properties,however, the zero band gap of monolayer graphene might limit its furtherelectronic and optoelectronic applications. Herein, we have successfullysynthesized monolayer silicon-doped graphene (SiG) in large area by chemicalvapor deposition method. Raman spectroscopy and X-ray photoelectronspectroscopy measurements evidence silicon atoms are doped into graphenelattice with the doping level of 3.4 at%. The electrical measurement based onfield effect transistor indicates that the band gap of graphene has been openedby silicon doping, which is around 0. 28 eV supported by the first-principlecalculations, and the ultraviolet photoelectron spectroscopy demonstrates thework function of SiG is 0.13 eV larger than that of graphene. Moreover, theSiG/GaAs heterostructure solar cells show an improved power conversionefficiency of 33.7% in average than that of graphene/GaAs solar cells, whichare attributed to the increased barrier height and improved interface quality.Our results suggest silicon doping can effectively engineer the band gap ofmonolayer graphene and SiG has great potential in optoelectronic deviceapplications.