High resistive tunnel junctions for the room temperature operating single electron transistors fabricated using chemical oxidation of tungsten nano particles

We present the fabrication of high resistive tunnel junctions used for the demonstration of room temperature operating single electron transistor devices with multiple tunnel junctions participating in the conduction process. The tunnel junctions were fabricated by the chemical oxidation of tungsten nano-islands in peracetic acid. The oxidation of tungsten nano-islands with an 8.0 nm average diameter resulted in tungsten oxides 2.0 to 9.0 nm thickness depending on the oxidation time of tungsten nano-islands. The fabricated W-WO₃ tunnel junctions have an estimated tunnel resistance of ~29GΩ with the charging energies of 160.0 meV for the device, with the effective capacitance of the device estimated at 0.499 aF. The capacitance of the individual junction was found to be 0.947 aF. The SET devices fabricated using these highly resistive tunnel junctions exhibited clear Coulomb blockade and Coulomb oscillations at room temperature. The effective barrier height of the tunnel junctions was calculated to be ~2.3eV.