Near-Zone Field Effect of FIR Laser Radiation on Tunnel Current through the Schottky Barrier under Plasma Reflection Condition

Abstract

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 shown that the observed photoresistive effects are caused by ponderomotive forces of the radiation field on the free electron plasma in the junctions. The change of tunnel conductance rises linearly with increasing intensity at low power levels and proceeds into a strongly superlinear dependence at high intensities. It is shown that this superlinearity is a result of an enhancement of the local radiation field in the near zone of diffraction by inhomogeneities at the metal–semiconductor interface and depends strongly on the roughness of the metal electrode. Experimental results are compared to a nonlinear extension of the theory of electron redistribution due to the radiation pressure.

Giant Terahertz Photoconductance of Quantum Point Contacts in the Tunneling Regime

“…Assuming that this field results in a voltage drop over several 100 nm distance we obtain v ac 0.1, yielding a weaker photoconductivity variation as compared to the experiment. Better agreement can be achieved by taking into account that the field in the vicinity of the QPC is enhanced by the presence of the metallic electrodes, since the field enhancement factor 10 cannot be ruled out in our structures [20][21][22][23][24]. Moreover, an important feature of our system is that, besides the direct action of the x-component of the radiation electric field E x on the electrons, the terahertz radiation also results in a reduction of the barrier height due to an electric field component normal to the quantum well plane E z .…”

Highly superlinear giant terahertz photoconductance in GaAs quantum point contacts in the deep tunneling regime

“…Assuming that this field results in a voltage drop over several 100 nm distance, we obtain v ac 0.1, yielding a weaker photoconductivity variation as compared to the experiment. Better agreement can be achieved by taking into account that the field in the vicinity of the QPC is enhanced by the presence of the metallic electrodes since the field enhancement factor 10 cannot be ruled out in our structures [17,[20][21][22][23][24][25].…”