Growth of quasi-1D PtSe2 semimetallic nanowire for high-performance bi-directional photodetection
One-dimensional (1D) and quasi-1D platinum diselenide (PtSe2) exhibit enhanced quantum confinement and surface effects, leading to distinctive electronic and optical properties. However, efficient synthesis of high-quality quasi-1D PtSe2 with controlled dimensionality and orientation remains challenging. Here, we report the first successful synthesis of quasi-1D PtSe2 via a carrier-gas-assisted chemical vapor deposition (CVD) approach. By optimizing hydrogen concentration, we achieved highly oriented and crystalline quasi-1D PtSe2, which exhibits exceptional thermodynamic stability along the (110) crystal plane. Electrical characterization reveals that 2D few-layer PtSe2 exhibits p-type semiconductor properties, while quasi-1D multilayer PtSe2 displays semimetallic behavior. Due to quantum confinement effects, both materials exhibit similar carrier mobilities. In photodetection at 1550 nm, 2D PtSe2 exhibits conventional positive photoresponse with a maximum responsivity of 97.0 A/W. In contrast, quasi-1D PtSe2 demonstrates unique negative photoresponse, achieving a maximum responsivity of 194.2 A/W, attributed to its semimetallic nature and significant surface traps. Temperature-dependent photoresponse measurements at various power levels further confirm that the negative response originates from a defect-assisted photogating effect, the strength of which exhibits significant temperature dependence under high-power illumination. This work not only fills a gap in the synthesis of 1D PtSe2 but also provides a novel material platform for developing advanced infrared optoelectronic devices.