Quantized conductance with a step size of less than ${\mathit{e}}^2$/h, which increases linearly with increasing perpendicular magnetic field, and resonant tunneling through an impurity state in a long silicon inversion wire have been observed at 4.2 K. This is approximately understood by considering a quantum point contact, an impurity state, and a large gate-voltage-dependent resistor in series.

• Received 9 March 1992

DOI:https://doi.org/10.1103/PhysRevB.45.13799