  We describe a method for creating atomic-scale electric contacts. A metal
source is deposited on two insulating substrates separated by a 70 nm gap.
Electric conductance across the gap is monitored, while protrusions from the
bulk extend into the gap and reach corresponding protrusions on the other side
of the gap. When the voltage across the gap is large, a pair of corresponding
protrusions assembles into a point contact, via equilibrium between
electrostatic attraction and a maximum sustained current. The current voltage
characteristics of the point contact display crossover from weak link into
tunneling junction when its conductance is near 2e2/h, indicating that the
point contact is atomic-scale.
