A novel nanofabrication technique for the array of nanogap electrodes

We demonstrate that nanogap between gold and poly-Si electrodes can be defined without using e-beam lithography. The technique showed that reproducible nanogap distance of around 10 nm on the six-inch wafer be easily obtained. Binding of 15 nm gold nanoparticles across the 10 nm electrodes leading to a drastic change of the electrical conductance has also been observed. The key fabrication process was utilized the spacer as sacrificial layer to define the distance of the nanogap between the electrodes. Figure 1 shows the fabrication procedure of array of nanogap electrodes. Structures of nanogap were formed in the crossing region of two electrodes after removal of the sacrificial material, as shown in fig 2. The feature size of nanogap electrodes fabricated using this technology is mainly limited by the thickness of spacer. Further experiments have shown that a 10 nm gap can be successfully obtained, as shown in fig. 3(a). Then, deposition of gold nanoparticles on nanogap electrodes after functionalized the surface of electrodes with amino group was performed for investigation of electrical properties, as shown in fig. 3(b). Figure 3(c) shows a measurement of the I-V characteristics of a typical device before and after gold colloidal interaction on the nanogap. As can be clearly identified, the interaction with colloids leads to a drastic change of the device conductivity. Under bias of 3 volts, the current changes from 2 pA to 30 nA after deposition of 15 nm gold nanoparticles. We believed that this technique can be contributed to the development of high-density nanogap electrodes for applications in biomolecular or nanoparticles detection.