Artificial Graphene in Nano-patterned GaAs Quantum Wells*

We report the realization of artificial graphene (AG) in a 2D electron gas in a highly tunable semiconductor quantum well system. Very short period (as small as 40 nm) honeycomb lattices were formed in a GaAs heterostructure by electron beam lithography followed by dry etching. Characterization of the AG samples by photoluminescence at low temperature (about 4K) indicates modulation of 2D electron states. Low-lying electron excitations observed by resonant inelastic light scattering and interpreted with a calculated AG band structure confirm the formation of AG bands with a well-defined Dirac cone, evidence for the presence of massless Dirac fermions. These results suggest that engineered semiconductor nano-scale structures can serve as advanced quantum simulators for probing novel electron behavior in low dimensional systems.