SPATIAL EVOLUTION OF HOT-ELECTRON RELAXATION IN QUANTUM HALL CONDUCTORS

We have analyzed the energy relaxation of hot electrons in the prebrea kdown regime of the quantum Hall effect. Hot electrons, generated by a periodic set of constrictions, are injected into two-dimensional elec tron systems (2DES's) of various mobilities, with Hall fields below th e breakdown value. The resistivity of the 2DES is measured as a functi on of the distance from the injection front. The results are compared with calculations on the basis of a nonequilibrium between the excitat ion and relaxation of hot electrons. Energy relaxation lengths from 0. 3 to 3 mu m were deduced, which increase with the mobility and are com parable to the mean free path. [S0163-1829(98)51936-4].