National Research Council of Canada. National Institute for Nanotechnology
light; emission; graphene; transistor; surface plasmon; hot carrier; Čerenkov
We present an experimental study of the light-emitting properties of graphene field effect transistors in the visible and near infrared spectral range. Using spectroscopic and imaging techniques, the effects of source–drain and gate voltages on the spectrum and location of the light emission were investigated. Raman spectroscopy, electronic measurements, and scanning electron microscopy combined with energy dispersive x-ray spectroscopy were used to characterize the devices. Results show that the spectral features (peak spectral intensity and wavelength) were controllable via applied source–drain or gate voltages, while the physical location of the light emission was strongly affected by scattering sites, including defects, nanoparticles, and edges. A possible explanation of the observed light emission is the outcoupling of surface plasmons excited by hot carriers in graphene according to the quantum Čerenkov effect. Hence, this work suggests the feasibility of all-electrical graphene devices for applications in light emission and plasmonics.