In$_{2}$O$_{3}$ nanowire based field effect transistor for biological sensors.

Semiconductor nanowires (NWs) are attracting considerable attention due to their nanoscale dimensions and enormous surface-to-volume ratios. Many applications have been demonstrated in toxic gas, protein, small molecule and viruses sensing because of their superior sensing performances. Indium oxide (In$_{2}$O$_{3})$ NWs have been successfully applied for toxic gas and small organic molecule sensing. In our experiment, In$_{2}$O$_{3}$ NWs based field effect transistors (FET) are fabricated for virus (Ricin) detections. Single-crystalline In$_{2}$O$_{3}$ NWs with diameters around 100 nm were synthesized by the thermal evaporation. The nanodevice based on In$_{2}$O$_{3}$ NWs bridges the source/drain electrodes with a channel length of $\sim $5 $\mu $m. Basic transport properties of devices were measured before biological detection. The I-V curves with the gate voltage V$_{g}$=0 shows good ohmic contact and the resistance is about 10 M$\Omega $. The back-gate effect on the conductivity showed that In$_{2}$O$_{3}$ NW is working as $n$-type channel with obvious back-gate effect, which is much stronger than the reported results. The nanodevices used as virus detection will be also discussed.