A simple method for preparing a TiO2-based back-gate controlled N-channel MSM–IGFET UV photodetector†
Atomic layer deposition (ALD) is used to grow a TiO2 film on a SiO2/Si substrate. A 50 μm N-channel, gate-regulated UV photodetector was fabricated by a simple process of air calcination and mask plating the electrode. The calcination process was found to improve the crystallinity of TiO2, reduce the concentration of the majority of carriers, and increase their mobility (∼0.05 cm2 V−1 s−1). The photoelectric performance of the as-prepared device is improved by about 200 times after calcination under the same test conditions. The as-prepared device has both gate voltage tunable properties of the insulated gate field effect transistor (IGFET) and a high gain (2–3 × 104). At a gate voltage of 8 V and a drain voltage of 3 V, the external quantum efficiency of the device to 0.5 mW cm−2 of 330 nm UV light is ∼2003%. The preparation of such a MSM–IGFET device will be helpful in reducing the device fabrication cost, optimizing the device performance, and promoting the application of photodetection.