Current-Voltage Characteristics in Nanoscale Tunnel Junctions Utilizing Thin-Film Edges

We have derived a formula for current density-voltage (J-V) characteristics in nanoscale tunnel junctions, consisting of thin insulating barriers sandwiched between two thin metal films whose edges are crossing. As a result of the calculation of J-V characteristics, the current density decreases with decreasing the metal thickness below 30-40nm due to the quantization of the out-of-plane direction in the metal films. Moreover, as a result of the fabrication of Ni/NiO/Ni nanoscale tunnel junctions with a junction area of 24 x 24 nm(2), we have found that experimental J-V characteristics show a good fit to calculation results with a barrier height of 0.8 eV and a barrier thickness of 0.63 nm. These results indicate that the derived formula is useful for the evaluation of the barrier height and the barrier thickness and our fabrication method can be expected as a new technique for the creation of nanoscale tunnel junctions. (C) 2010 The Japan Society of Applied Physics