Quantized conductance in ballistic constrictions at 30 K

Quantized conductance in a split-gate structure is observed at a temperature of 30 K. Plateaus in the conductance as a function of gate voltage are observed at 30 K, while traces of the first step exist as high as 44 K. Plateaus are also seen with a bias of up to 12 mV across the constriction. This performance is made possible by placing the two-dimensional electron gas (2DEG) 30 nm below the surface, and a gate separation of 100 nm. Simulations of this structure, using two-dimensional, self-consistent solutions of Schrödinger’s and Poisson’s equations, suggest subband separations of 10 meV.