Selective Growth of Type-II Weyl-Semimetal and Van der Waals Stacking for Sensitive Terahertz Photodetection

The emergence of novel topological semimetal materials, accompanied by exotic non-equilibrium properties, not only provides a fertile playground for a fundamental level of interest but also opens exciting opportunities for inventing new applications by making use of different light-induced effects such as nonlinear optics, optoelectronics, especially for the highly pursued terahertz (THz) technology due to the gapless electronic structures. Exploring type-II Weyl semimetal endowed with the richness of quantum wavefunction and peculiar band structure, underlie strong nonlinear coupling with THz waves. Here, the selective growth of type-II Weyl semimetal NbIrTe4 by means of a self-flux approach is reported, which hosts strongly tilted Weyl cones and exotic Fermi arcs. The oscillating THz field induced by the antenna is engineered in terms of planar metal-topological semimetal-metal structure, along with van der Waals stacking, which allows for self-powered photodetection at room temperature. The results elucidate the superior performance of NbIrTe4-graphene heterostructure-based photodetectors with responsivity up to 264.6 V W-1 at 0.30 THz, fast response of 1 mu s as well as low noise equivalent power.0.28 nW Hz(-0.5) is achieved, already exhibiting high-quality imaging at THz frequency. The results promise superb impacts in exploring topological Weyl semimetals for efficient low-energy photon harvesting.