Modulating the Transport Properties of Metal Oxide Nanofibers Transistors by Controlling the Grain Size

Although SnO₂ nanofibers (NFs) are one of the good candidates as active materials for next-generation consumable electronics, these NFs based devices still suffer from insufficient on-off current ratios, large and negative threshold voltages ( V_TH), leading to high energy consumption and rather complicated circuit design. Here, SnO₂ NFs field-effect transistors (FET) were fabricated by an electrospinning technique. The device performance can be precisely manipulated by controlling the crystal grain size in the NFs. This is done by simply adjusting the annealing holding time to achieve high-performance enhancement mode. For the optimal annealing holding time of 60 min, the grain size of NFs is about 11 nm, and the devices exhibit the best electrical performance, including a small and positive V_TH (≈ 2.2 V), a large switching current ratio (I_ON/I_OFF ≥ 10⁶), and proper carrier mobility ( μ_FE) (≈ 2.3 cm² V^-1 s^-1). Moreover, this approach is universal and can be applied to optimize other metal oxide semiconductors such as ZnO NFs. This simple and facile method indicates that adjusting annealing holding time is a potential way to control the grain size to achieve low voltage operation and enhancement mode 1D metal oxide FETs.