Improvement of sensitivity of graphene photodetector by creating bandgap structure

Zhang Ni-Zhen¹, He Meng-Ke¹, Yu Peng^{1, †}, Zhou Da-Hua^{2, ‡}

(color online) Raman spectra of graphene of (a) monolayer graphene, (b) several layers of graphene, (c) Ti layer deposited on graphene, and (d) defective graphene.