Two-dimensional (2D) materials with narrow band gaps (∼0.3 eV) are of great importance for realizing ambipolar transistors and mid-infrared (MIR) detections. However, most of the 2D materials studied to date have band gaps that are too large. A few of the materials with suitable band gaps are not stable under ambient conditions. In this study, the layered Nb2SiTe4 is shown to be a stable 2D material with a band gap of 0.39 eV. Field-effect transistors based on few-layer Nb2SiTe4 show ambipolar transport with a similar magnitude of electron and hole current and a high charge-carrier mobility of ∼100 cm2 V–1 s–1 at room temperature. Optoelectronic measurements of the devices show clear response to an MIR wavelength of 3.1 μm with a high responsivity of ∼0.66 AW–1. These results establish Nb2SiTe4 as a good candidate for ambipolar devices and MIR detection.
Nb₂SiTe₄, a layered narrow-bandgap van der Waals semiconductor, has been attracting more and more attention due to its high carrier mobility and excellent optical absorption properties. In this study, we exploited this material in the photoelectrochemical type photodetector (PD) to investigate its potential for energy saving optoelectronics. A simple high-temperature solid-state reaction method was utilized for synthesizing high quality Nb₂SiTe₄ crystals, and liquid-phase exfoliation was employed to prepare the corresponding nanosheets for the device construction. The photoelectric performances of the Nb₂SiTe₄ nanosheet PDs were characterized in a three-electrode system and broad spectral responses ranging from 400 to 900 nm were detected. The effects of dispersants, electrolyte, as well as light power density on the device performance were systematically investigated. At 0 V bias voltage, an optimal performance of the PDs was obtained in acidic testing environment upon illumination of the 400 nm light, and the highest photocurrent density of 0.72 μA cm⁻² and responsivity of 7.71 µA W⁻¹ were achieved. Besides, the device demonstrated fine long-term cycling and air stabilities. This work implies the potential of Nb₂SiTe₄ for being applied in broadband photodetection of self-powering devices.
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