MS-8-P-3402 In-situ TEM with electrical characterisation of tapered InAs nanowires with Ohmic contacts

Semiconductor nanowires have attracted much interest due to their outstanding properties as building blocks in nanoelectronic devices [1]. Among these, InAs nanowires with a smaller band gap and higher electron moblility exhibits particular potential for high performance transistors, memory, interconnects and sensors. Since a high stability of these nanowires (NW) is required, it is important to perform failure tests. There are some reports on in-situ TEM with electrical failure tests [e.g. 2-5] on the electrical properties as well as the failure tests of semiconductor nanowires, but these were done with an in-situ STM tip in a TEM holder. In this set-up the electrical contact of the STM tip with NWs is realized by moving the STM tip to contact one side of the NWs However, it is difficult to control the contact quality as well the contact resistance between the NWs and STM tip. We have developed an alternative set-up allowing the investigation of the electrical properties as well as breakdown of tapered InAs nanowires with Ohmic contacts using a homemade in-situ TEM biasing holder. Furthermore, by having more than two contacts on the nanowire we could also measure the contact resistance of the applied contacts (except for the most outer contacts), which showed that the contact were Ohmic. By measuring a number of segments of a tapered nanowire we determined that the electrical resistivity is constant (~10-2Ω·cm) for nanowires with diameter larger than 120nm and gradually increases for thinner sections. The electrical breakdown started in the position close to the cathode side, and starts with electromigration of In, followed by the sublimation of arsenic. The critical current density for breakdown was about 106 A/cm2. The set-up for electrical measurement is shown in Fig. 1(a). The electrodes deposited on silicon nitride membrane consist 5 nm Cr and 95 nm Au with a width of 500 nm and separated by 4 µm from each other. Then of 500nm wide 5 µm long gaps were created by drilling holes on the membrane using a FIB. Next, a single tapered nanowire was transferred onto the electrodes by using an ex-situ nano-manipulator. Finally platinum was deposited on top of the joints between the nanowire and the electrodes with FIB to ensure a good contact quality. REFERENCES 1. S. W. Nam, et al, Science 336, 1561(2012) 2. T. Westover, et al, Nano Lett. 9, 257 (2009). 3. Z. Xu, D. Golberg, and Y. Bando, Nano Lett. 9, 2251 (2009). 4. K. Davami, et al, Chem. Phys. Chem. 13, 347 (2012) 5. J. Zhao, H.Y. Sun, S. Dai, Y. Wang, and J. Zhu, Nano Lett. 11, 4647 (2011).