sentences:  Research is exploring the creation of quantum dots by changing the width of GNRs at select points along the ribbon, creating quantum confinement.Heterojunctions inside single graphene nanoribbons have been realized, among which structures that have been shown to function as tunnel barriers.Graphene nanoribbons possess semiconductive properties and may be a technological alternative to silicon semiconductors capable of sustaining microprocessor clock speeds in the vicinity of 1 THz field-effect transistors less than 10 nm wide have been created with GNR – "GNRFETs" – with an Ion/Ioff ratio >106 at room temperature.