We have shown that a lateral superlattice of dots of period 40 nm can be fabricated and have defined a 60 nm period hexagonal lateral surface superlattice of dots over a high-mobility two-dimensional electron gas. With a negative voltage on the gate a honeycomb potential is created around the dots. The pattern is produced with electron beam lithography by stitching together superlattice regions of area (0.5 μm).2 At gate voltages close to zero the Shubnikov–de Haas peaks are split into subbands with corresponding structure in the Hall voltage. Close to pinch-off, periodic peaks in the conductance versus gate voltage are seen whenever one electron is removed from the 0.5 μm square region. The electrons are localized in this area by the error in the stitching of the fields. There is a sharp drop in conductance when the carrier concentration is such that there is one electron per unit cell, which may indicate the electrons are condensing in a lattice commensurate with the applied periodic potential.
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Smith et al. (1992) studied this question.