Monte Carlo simulation of electron transport in a graphene diode with a linear energy band dispersion

Electron transport and energy relaxation in a 100-nm channel n-n-n monolayer graphene diode were studied by using semiclassical Monte Carlo particle simulations. A diode with a conventional parabolic band and an identical geometry and scattering process was also analyzed in an attempt to confirm that the characteristic transport properties originated from the linear energy band structure. We took into account two scattering mechanisms: isotropic elastic scattering and inelastic phonon emission. The carrier velocity distributions in the two diodes show remarkable differences reflecting their band dispersions. Electron velocity in the monolayer graphene diode is high in the channel region and remains almost constant until the energy relaxation begins. Inelastic scattering does not reduce electron velocity so severely, whereas elastic scattering significantly decreases it through backscattering of hot electrons with high kinetic energy. Elastic scattering also degrades the ballisticity and the drain current; however, increasing the inelastic scattering offsets these effects. We found that elastic scattering should be suppressed to improve the performance of graphene devices.