Structure and transport characteristics of tunnel junctions with hybrid semiconductor barriers with quantum dots

We propose to realize MoRe/SiO_x(W)/MoRe hybrid junctions by using self-organization effects for the creation of quantum dots (tungsten clusters) in the semiconductor barriers consisting of a mixture of silicon and silicon oxide. Current-voltage characteristics of the MoRe/SiO_x(W)/MoRe samples have been measured in a wide voltage range from -900 to 900 mV at temperatures from 4.2 to 77 K. At low temperatures and for a comparatively small W content in the hybrid barrier, the heterostructures exhibited current-voltage curves of an unusual shape. Single or several current peaks caused by electron tunneling through the allowed states in the barrier have been observed in the transport characteristics. With increasing temperature, superconducting fluctuations in the MoRe electrodes become unimportant, and the current-voltage curve of a heterostructure follows the Ohm law. At last, we present theoretical description of the charge transport in such inhomogeneous systems with account of many-electron processes.