Wafer-Scale 1T′ MoTe₂ for Fast Response Self-Powered Wide-Range Photodetectors

The semimetal-based photodetector possesses the intrinsic advantage of high response speed, low power consumption, and wide-range photoresponse. Here, we report the synthesis and application of 1 inch wafer-scale polycrystalline few layer 1T′-MoTe₂ on the SiO₂/Si substrate by employing a modified chemical vapor deposition method of predeposition of precursors. A continuous film with seamlessly stitched micrometer scale grains has been realized, and the pure 1T′ phase was confirmed by Raman spectroscopy. An asymmetric metal electrode photodetector device of Pd-MoTe₂-Au was designed and fabricated by using shadow mask-assisted UHV deposition. By measuring the self-powered photocurrent under the illumination of Xe lamp, we show that the device is sensitive to a wide spectra range (λ = 320-1200 nm) while maintaining high performance of the ON/OFF ratio (∼10³), responsivity (1.2 A/W), and specific detectivity (7.68 × 10¹² Jones). Under 450, 648, and 850 nm pulsed laser illumination, the response time achieves tens of microsecond scale. The device shows polarized photoresponse as well.