High-Performance Single CdS Nanobelt Metal-Semiconductor Field-Effect Transistor-Based Photodetectors

We have demonstrated for the first time that under suitable gate biases, single CdS nanobelt (NB) metal-semiconductor field-effect transistors (MESFETs) can serve as high-performance photodetectors. When a gate voltage near to the threshold voltage of the MESFET under illumination is supplied, the single NB MESFET-based photodetectors exhibit high photosensitivity, such as ultrahigh photoresponse ratio ( I light / I dark ≈ 2.7 × 10 6 ) (among the best values reported so far for single NB/NW photodetectors), high current responsivity (∼2.0 × 10 2 A/W), high external quantum efficiency (∼5.2 × 10 2 ), and fast photoresponse: with rise and decay times of ∼137 and ∼379 μs, respectively. The working principle of the single NB MESFET-based photodetectors as well as the reasons for the enhancement in performance is discussed. Our accomplishment can be easily extended to other 1D semiconductor nanomaterials. All the above results show that the single NB/nanowire (NW) MESFETs can be a promising candidate for novel photodetectors and photoelectronic switches.