|
Photodetectors capable of detecting visible, infrared, and terahertz radiation are essential components in various optoelectronic applications. Traditional semiconductor-based photodetectors are often limited in their spectral detection range by their restricted bandgap. While photodetectors utilizing black phosphorus and graphene can achieve broad-spectrum detection, these are subject to the poor environmental stability of black phosphorus and the limited light absorption capacity of graphene. Platinum ditelluride (PtTe2), classified as a type II Dirac semimetal, exhibits exceptional properties including strong light absorption, high carrier mobility at room temperature, and a zero bandgap, making it a promising candidate for photodetection applications in the infrared and terahertz regions. In this study, large-area uniform PtTe2 thin films were epitaxially grown using a simple tellurium-vapor transformation approach. By harnessing the wideband absorption capabilities and superior carrier mobility of PtTe2, a PtTe2/Si vertical heterojunction photodetector and a dual-bow-tie-type antenna enhanced THz detector were proposed, enabling the fabrication of ultrabroadband photodetectors from visible to terahertz. Through optimization of the device barrier height of the PtTe2/Si vertical heterojunction devices, carrier interfacial diffusion in the dark was suppressed, the recombination probability of photogenerated carriers was reduced, while the rapid collection of photogenerated carriers was facilitated, resulting in a wideband response spanning from 405 to 5000 nm. To enhance the absorption rate of PtTe2 in the THz band, a dual-bow-tie-type antenna electrode was utilized to improve the photoresponse of the device in this frequency range, leveraging the driving capability of Dirac fermions simultaneously to achieve photoresponse in the 0.1 THz band. With a carefully designed device structures, the photodetector demonstrated a high specific detectivity (6.78×108 @1310 nm, 4.4×107 @0.1 THz) and a relatively fast response speed (~ ms) across a broad spectral range. The large-area fabrication capability and high specific detectivity of the device enabled room-temperature infrared imaging applications with exceptional image clarity. This approach, compatible with CMOS processes, presents a novel design concept for high-performance room-temperature photodetector from visible to terahertz detection utilizing topological semimetal materials.
|
