Modeling of spectral shift in Raman spectroscopy, photo- and electro-luminescence induced by electric field tuning of graphene related electronic devices

The continuous tuning of the emission (absorption) spectra of the excitons in graphene field-effect transistors by the gate (drain) voltage is of great technological significance. And its physical mechanism still remains to be unraveled. A new physical model of the electric field dependent exciton energy and its impacts on the emission (absorption) spectra is proposed based on the ambipolar transport theory with the energy balance assumption. By comparing the shift in the emission (absorption) peak predicted by the proposed model with those experimental data reported in the literature, we could conclude that the energy relaxation of the excitons plays a dominant role in the spectral shift. Thus, the energy relaxation of the excitons is a physical origin for the gate (drain) voltage dependent spectral shift. The proposed model predicates that the gate control of the spectral shift depends on the channel length, the gate oxide thickness, the dielectric constant of the gate oxide, the thickness of the graphene layer, and the dielectric constant of the graphene, whereas the drain control of the spectral shift is mainly determined by the channel length. These findings will benefit to better understand the effect of the electric field on the emission (absorption) spectrum.

The peak position as a function of the gate voltage.103