Graphene has been provided us opportunities to explore exotic transport effect in low-energy condensed matter systems and the potential of carbon based novel device applications. In this presentation I will discuss the exotic quantum transport behavior discovered in graphene nanostructures in the relation to the device applications beyond CMOS operation. In particular, I will present quantum carrier collimation both of which appear even at room temperature employing graphene lateral heterojunction. In addition, I will discuss the enhanced device performance of suspended graphene devices and graphene with a novel substrate.