SUPERLATTICE TRANSPORT IN INTENSE TERAHERTZ ELECTRIC-FIELDS

The low DC field conductance and the nonlinear I-V characteristics of GaAs/Al0.70Ga0.30As superlattices have been measured in the presence o f intense electric fields produced by UCSB's free-electron lasers. The DC conductance exhibits oscillatory behavior as a function of teraher tz field strength that resembles the zeroth-order Bessel function, J0( edE(AC)/HomegaBAR), where e, d, and E(AC) are the electron charge, sup erlattice period and AC field strength, respectively. The I-V characte ristics, measured between 600 GHz and 3.1 THz, display new steps and p lateaus. The dependence of the new structure of frequency suggests the presence of new conduction channels that are most naturally assigned to photon-mediated sequential tunneling.