Ultrasensitive Near-Infrared Polarization Photodetectors with Violet Phosphorus/InSe van der Waals Heterostructures

Broadband photoresponse based on a Te/CuInP2S6 ferroelectric field-effect transistor

Narrow bandgap two-dimensional (2D) semiconductors have garnered significant attention for their potential applications in next-generation optoelectronic devices. However, only few previous studies have manipulated electronic polarization, such as ferroelectric polarization and spin polarization, in conjunction with photodetectors. In this work, we designed Te ferroelectric field-effect transistors (Fe-FETs) that exhibit a clear counterclockwise hysteresis loop in transfer characteristic curves. The device achieves an ultrabroad band photoresponse from 637 nm to 10.6 μm and a high photoresponsivity (R) of 10.2 A W-1 under 1 V bias. Importantly, under 637 nm laser irradiation, the device shows a very fast speed with a rise time (τr) of 3.86 μs and decay time (τd) of 6.28 μs. The proposed Te Fe-FET device provides a strategy for designing high-performance photodetectors with extensive applications.

Sensitive photodetection in a violet phosphorus tunnel junction

Two-dimensional violet phosphorus (VP), a semiconductor with a tunable bandgap and anisotropic crystal structure, has demonstrated significant potential for photodetector applications due to its extremely high light on/off ratio and anisotropic light detectivity. Nonetheless, its performance is hindered by substantial intrinsic resistance, resulting in low photoresponsivity. In this work, we introduce a gate-tunable vertical tunnel junction device that employs thin-film violet phosphorus as the tunneling barrier and graphene as the electrode. This configuration shortens the transport path for photo-excited charge carriers in violet phosphorus, leading to a decreased recombination rate and a marked enhancement in photoresponsivity. Our device maintains a light-to-dark current ratio exceeding 2 × 105 and achieves an optimized photoresponsivity of 0.58 A/W at the 532 nm excitation by fine-tuning the bias and gate voltages. Furthermore, we detect a noticeable photocurrent signal even when the excitation photon energy falls below the bandgap of violet phosphorus. The infrared photoresponse diverges from the visible-light response in both temperature and polarization dependencies, indicating two distinct underlying mechanisms for photocurrent generation in these spectral ranges. This multi-mechanism detection strategy expands the wavelength capabilities for violet phosphorus-based photodetectors, opening new avenues, to the best of our knowledge, for advanced optoelectronic devices.

Development and challenges of polarization-sensitive photodetectors based on 2D materials

Polarization-sensitive photodetectors based on two-dimensional (2D) materials have garnered significant research attention owing to their distinctive architectures and exceptional photophysical properties. Specifically, anisotropic 2D materials, including semiconductors such as black phosphorus (BP), tellurium (Te), transition metal dichalcogenides (TMDs), and tantalum nickel pentaselenide (Ta2NiSe5), as well as semimetals like 1T'-MoTe2 and PdSe2, and their diverse van der Waals (vdW) heterojunctions, exhibit broad detection spectral ranges and possess inherent functional advantages. To date, numerous polarization-sensitive photodetectors based on 2D materials have been documented. This review initially provides a concise overview of the detection mechanisms and performance metrics of 2D polarization-sensitive photodetectors, which are pivotal for assessing their photodetection capabilities. It then examines the latest advancements in polarization-sensitive photodetectors based on individual 2D materials, 2D vdW heterojunctions, nanoantenna/electrode engineering, and structural strain integrated with 2D structures, encompassing a range of devices from the ultraviolet to infrared bands. However, several challenges persist in developing more comprehensive and functional 2D polarization-sensitive photodetectors. Further research in this area is essential. Ultimately, this review offers insights into the current limitations and challenges in the field and presents general recommendations to propel advancements and guide the progress of 2D polarization-sensitive photodetectors.