High-Responsivity Multiband and Polarization-Sensitive Photodetector Based on the TiS₃/MoS₂ Heterojunction

Abstract

Two-dimensional (2D) material photodetectors have received considerable attention in optoelectronics as a result of their extraordinary properties, such as passivated surfaces, strong light− matter interactions, and broad spectral responses. However, single 2D material photodetectors still suffer from low responsivity, large dark current, and long response time as a result of their atomic-level thickness, large binding energy, and susceptibility to defects. Here, a transition metal trichalcogenide TiS 3 with excellent photoelectric characteristics, including a direct bandgap (1.1 eV), high mobility, high air stability, and anisotropy, is selected to construct a type-II heterojunction with few-layer MoS 2 , aiming to improve the performance of 2D photodetectors. An ultrahigh photoresponsivity of the TiS 3 /MoS 2 heterojunction of 48 666 A/W at 365 nm, 20 000 A/W at 625 nm, and 251 A/W at 850 nm is achieved under light-emitting diode illumination. The response time and dark current are 2 and 3 orders of magnitude lower than those of the current TiS 3 photodetector with the highest photoresponsivity (2500 A/W), respectively. Furthermore, polarized four-wave mixing spectroscopy and polarized photocurrent measurements verify its polarization-sensitive characteristics. This work confirms the excellent potential of TiS 3 /MoS 2 heterojunctions for air-stable, highperformance, polarization-sensitive, and multiband photodetectors, and the excellent type-II TiS 3 /MoS 2 heterojunction system may accelerate the design and fabrication of other 2D functional devices.

A two-dimensional Te/ReS2 van der Waals heterostructure photodetector with high photoresponsivity and fast photoresponse

“…The decrease of all the above metrics with increasing light intensity is probably due to the existence of trap states at the interface between Te/ReS 2 and the substrate, which is a common phenomenon in vdWH based photodetectors. 38,44,45 Under relatively low intensity conditions, the interface states will be occupied by the holes separated from the photogenerated electron-hole pairs. As the incident light intensity increases, an increasing number of electron-hole pairs is generated, indicating the diminishing of hole-trap states at the surface.…”

“…37 The value of α is less than 1 (0.51) due to the probability of carrier recombination and the existence of trap states at the junction interface. 38 With the increase of the laser power density, the adsorption gradually saturates, leading to a decreased adsorption coefficient. Besides, the plot of responsivity ( R λ ) as a function of the power intensity was also fitted using the power law R λ ∼ P β ( β = −0.36).…”

“…5d, the dependence of photocurrents and responsivities at various power densities at zero bias can be fitted with the power laws I p ∼ P α ( α = 0.51, deviated from the ideal index of α = 1) and R λ ∼ P β ( β = −0.36), which is due to the probability of carrier recombination and the existence of trap states at the junction interface. 38 The calculated D * and on/off ratio for 660 nm laser irradiation at various incident powers are shown in Fig. 5e and f.…”

Low-dimensional van der Waals materials for linear-polarization-sensitive photodetection: materials, polarizing strategies and applications

“…Thus far, researchers have prepared numerous polarized photodetectors based on a variety of anisotropic 2D vdWMs, including group VA semiconductors [71, [125][126][127][128][129], nonprecious transition metal chalcogenides (MX 2 [130][131][132][133][134], MX 3 [135][136][137][138][139][140][141], MX 5 [142]), IIIA-VIA compounds [123,143,144], IVA-VA compounds [123,[145][146][147][148][149][150][151], IVA-VIA compounds [120,121,[152][153][154][155][156], precious transition metal chalcogenides [157][158][159][160][161][162][163][164], multielemental vdWMs [72, 73, 165-173], etc. For clarity, table 2 has summarized the key performance metrics of various 2D vdWM polarizationsensitive optoelectronic devices.…”

Polarization‐Driven Ultrafast Optical Switching in TiS3 Nanoribbons via Anisotropic Hot Carrier Dynamics

“…[43] This structural anisotropy opens up opportunities for creating innovative devices with added versatility. [42,44,45] In particular, TiS 3 exhibits strong optical anisotropy with remarkable linear dichroism and birefringence. [38,40] It has been demonstrated that TiS 3based photodetectors show high polarization selectivity and photoresponsivity.…”