Near-zone field effect of FIR laser radiation on tunnel current through the Schottky barrier under plasma reflection condition

Far infrared (FIR) radiation of high-power pulsed laser incident normal to the surface of GaAs/metal tunnel structures with a self-consistent Schottky barrier gives rise to a change in the tunnel conductance. It has been show n that the observed photoresistive effects are caused by ponderomotive forc es of the radiation field on the free electron plasma in the junctions. The change of tunnel conductance rises linearly with increasing intensity at l ow power levels and proceeds into a strongly superlinear dependence at high intensities. It is shown that this superlinearity is a result of an enhanc ement of the local radiation field in the near zone of diffraction by inhom ogeneities at the metal-semiconductor interface and depends strongly on the roughness of the metal electrode. Experimental results are compared to a n onlinear extension of the theory of electron redistribution due to the radi ation pressure.