TRANSVERSE TUNNELING TIME CONSTANT ESTIMATED FROM HOT-ELECTRON NOISE IN GAAS-BASED HETEROSTRUCTURE

Electric noise characteristics of a triple-heterojunction AlGaAs/GaAs/ AlAs/GaAs structure are measured at 10 GHz frequency for the electric field (less than or equal to 1.3 kV/cm) applied in the interface plane . The maximum in the dependence of the longitudinal diffusion coeffici ent (deduced from the spectral density of current fluctuations) is obs erved at 1 kV/cm and interpreted as being brought about by back-and-fo rth transverse tunnelling of hot electrons between the quantum wells s eparated by a thin AlAs barrier, the wells being characterized by diff erent electron mobility. The tunnelling time constant is found from th e height of the maximum and, independently, from the quenching of the maximum in short samples. Copyright (C) 1996 Published by Elsevier Sci ence Ltd