Characterizing individual SnO ₂ nanobelt field-effect transistors and their intrinsic responses to hydrogen and ambient gases

The intrinsic electrical properties of individual single-crystalline tin dioxide nanobelts, synthesized via catalyst-free physical vapor deposition, were studied and correlated to the surface oxygen deficiency with the presence of various ambient gases, especially hydrogen. Four-terminal field-effect transistor (FET) devices based on individual SnO ₂ nanobelts were fabricated with SiO ₂/Si as back gate and RuO ₂/Au as contacts. Four-probe I-V measurements verify channel-limited transistor characteristics and ensure that the hydrogen gas sensing reflect electrical modification of the nanobelt channel. The demonstrated results of the intrinsic SnO ₂ nanobelt based hydrogen sensor operating at room temperature provide useful information on the synthesis of room temperature chemo-resistive gas sensors with good sensitivity and stability. To evaluate the impact of surface gas composition on the electrical properties of SnO ₂ nanobelts, their temperature-dependent resistivity (ρ), effective carrier mobility (μ _eff) and effective carrier concentration (n _e) were determined under different oxygen concentrations.