Chemical Vapor Deposition-Grown Nonlayered α‑MnTe Nanosheet for Photodetectors with Ultrahigh Responsivity and External Quantum Efficiency

Development of new two-dimensional (2D) materials with high performance photoelectronic properties is critical for the future multifunctional and miniaturized optoelectronic devices. α-MnTe is an room-temperature antiferromagnetic, direct band gap p-type semiconductor with unique energy band structure and may have high photoelectric conversion efficiency and excellent photoelectric properties. However, controlled synthesis of the 2D α-MnTe single crystal has rarely been achieved so far. In this paper, 2D α-MnTe nanosheets with a NiAs-type hexagonal structure, a stable 2D nonlayered p-type semiconductor, are prepared for the first time via van der Waals epitaxy chemical vapor deposition (CVD) on mica. The thickness of 2D α-MnTe can be well tuned by the reaction temperature and gas flow. The photoelectric performance of the photodetector based on the 2D α-MnTe nanosheet shows that the 2D α-MnTe nanosheet based photodetector has an ultrahigh photoresponsivity (2599 A/W), external quantum efficiency (EQE, 8.065 × 10⁵%), and excellent photodetectivity (3.32 × 10¹² jones) at an illumination of 400 nm @ 0.062 mW/cm² at 3 V, which is one of best performances of 2D material based photodetectors. Our work provides a new avenue to high performance 2D optoelectronic devices.