Fabrication and characterization of SnO2 nanobelt field effect transistors

Single-crystalline SnO$_{2}$ nanobelts have been produced by thermal evaporation of oxide powders in a tube furnace without any chemical catalyst. Individual SnO$_{2}$ nanobelts with thicknesses of 30nm$\sim $300nm and lengths as long as several hundred $\mu $m were dispersed onto a doped Si/SiO$_{2}$ substrate, and multi-terminal metal electrodes were defined on a nanobelt using photolithography. An individual nanobelt was then characterized by measuring current--voltage characteristics as a function of temperature using 4-probe measurement. Temperature dependence of the resistivity is characteristic of a doped semiconductor. A field effect transistor (FET) is formed using a nanobelt as the channel and doped Si as the gate. Electrical measurements revealed characteristic behavior of an n-channel depletion-mode FET, with well-defined linear and saturation regimes, a threshold voltage of $\sim $-15V, and on/off ratio as high as 10$^{3}$. The channel mobility is estimated to be 25 cm$^{2}$/V$\cdot $s, and carrier concentration about 6x10$^{15}$ cm$^{-3}$. The results demonstrate the potential of using SnO$_{2}$ nanobelt to construct high performance nanoFET with possible applications as chemical and biological sensors. This work is supported by NSF NIRT grant ECS-0210332.