Role of carrier imbalance on electron-impurity scattering rate in double layer graphene system.

Theoretical investigation about the role of carrier imbalance in electron-impurity scattering rate in double layer graphene system (DLGS) at finite temperature using Boltzmann transport equation is presented. The effect of the carrier imbalance is incorporated through carrier concentration ratio(nr) which varies from 0.2 to 10. In DLGS, the two graphene sheets are separated by interlayer distance d = 5 nm and the system is immersed in a three-layered medium with top graphene layer being surrounded by air while bottom graphene layer is developed on an Al2O3 substrate. Results show that scattering rate increases with increasing carrier concentration ratio(nr) for nr>0.2 and the pattern of scattering rate variation is mostly similar to that of the intralayer scattering rate of second layer graphene. Moreover for 0.2 < nr < 7.4 scattering rate gets enhanced on increasing temperature from 0 K to 300 K but for nr > 7.4 scattering rate at 0 K is more than that of 300 K, representing a reversal in behavior. The results presented by this study will act as guidelines for experiments and applications of new functional atomically-thin devices. [ABSTRACT FROM AUTHOR]