Ultrasensitive flexible near-infrared photodetectors based on Van der Waals Bi2Te3 nanoplates

Abstract

As an emerging two-dimensional (2D) material, Bi2Te3 has exhibited great potential for the applications in electronic and optoelectronic devices due to its unique features as topological insulator and thus high electron mobility. However, the application of 2D Bi2Te3 nanostructures in flexible NIR (near infrared) photodetectors has barely been investigated. In this work, we present a study on NIR photodetectors based on 2D Bi2Te3 nanoplates, which are grown on mica substrates by Van der Waals epitaxy (vdWe) method. The vertical thickness of the Bi2Te3 nanoplates is as small as 12 nm, while the lateral size is as large as 18 μm. The flexible NIR photodetectors based on the 2D Bi2Te3 nanoplates present excellent device performance, including photoresponsivity, specific detectivity and photoconductive gain. Under the illumination of a NIR laser (an emission wavelength of 850 nm), the photoresponsivity, specific detectivity and photoconductive gain are determined to be up to 55.06 mA/W, 8.05 × 10−2 and 5.92 × 107 Jones, respectively. In addition, the device performance (photoresponsivity, detectivity, rising time and decay time) of the Bi2Te3 nanoplate photodetectors shows no obvious degradation after bending for 100 times and 300 times, indicating the great flexibility of the photodetectors based on Bi2Te3 nanoplates. These findings indicate that Bi2Te3 nanoplates have great potential for fabricating flexible NIR detectors with high detectivity and photoresponsivity.