Ab initio calculation of electron transport in armchair graphane nano structure containing graphene quantum dot

First principle quantum transport calculations have been performed for armchair graphane nano structures containing graphene quantum dots (QD) of increasing sizes. Each QD has been formed by creating vacancies in the H lattice of graphane. TranSIESTA has been used for calculating transport properties with nonequilibrium Green's function approach within density functional theory. Transmission functions, electron density of states and current-voltage characteristics have been calculated using graphene electrodes. Band structure, electron density of states and zero bias conductance (transmission function) have been found to be in consonance with each other. The current in V-I characteristics shows non linear fluctuating pattern and tends to saturate as the voltage is increased. The value of current is graphene QD size dependent. The current lies in the range of nano ampere (for QD consisting of 16 contiguous vacancies) to femto ampere (for QD consisting of 6 contiguous vacancies). (author)