It is shown that the potential drop and the delivery of the Joule heat in a point contact are separated in space, and that the amounts of Joule heat released on both banks of the contact are different if the banks have a different shape. A calculation of the electron distribution function and the Joule heat in a point contact is presented, assuming the voltage drop is much smaller than the Fermi energy. The calculations are done for the diffusive limit, and it is argued that the length scales for the potential drop and the energy relaxation are the same in the ballistic limit.

• Received 5 January 1995

DOI:https://doi.org/10.1103/PhysRevB.52.1882