Giant Superlinear Power Dependence of Photocurrent Based on Layered Ta₂NiS₅ Photodetector

Abstract

Photodetector based on two‐dimensional (2D) materials is an ongoing quest in optoelectronics. 2D photodetectors are generally efficient at low illuminating power but suffer severe recombination processes at high power, which results in the sublinear power‐dependent photoresponse and lower optoelectronic efficiency. The desirable superlinear photocurrent is mostly achieved by sophisticated 2D heterostructures or device arrays, while 2D materials rarely show intrinsic superlinear photoresponse. This work reports the giant superlinear power dependence of photocurrent based on multilayer Ta2NiS5. While the fabricated photodetector exhibits good sensitivity (3.1 mS W−1per □) and fast photoresponse (31 µs), the bias‐, polarization‐, and spatial‐resolved measurements point to an intrinsic photoconductive mechanism. By increasing the incident power density from 1.5 to 200 µW µm−2, the photocurrent power dependence varies from sublinear to superlinear. At higher illuminating conditions, prominent superlinearity is observed with a giant power exponent of γ = 1.5. The unusual photoresponse can be explained by a two‐recombination‐center model where density of states of the recombination centers (RC) effectively closes all recombination channels. The photodetector is integrated into camera for taking photos with enhanced contrast due to superlinearity. This work provides an effective route to enable higher optoelectronic efficiency at extreme conditions.

High-Detectivity and Broadband Photodetector Based on LiInP2Se6 Semiconductors

“…Furthermore, the dependence of photocurrent on light intensity can be fitted well by the power law I ph = αP θ , where I ph is the photocurrent ( I ph = I light – I dark , I light is the current under illumination, I dark is the dark current), α is a constant for a certain wavelength, P is the laser power density, and θ is a constant used to characterize the photoelectric sensitivity . As shown in Figure f, the fitted value of θ is 0.87, close to that for an ideal photodetector ( θ = 1), which might be counted as a complicated process of the generation, trapping, and recombination of the photoinduced carriers. , …”

“…24 As shown in Figure 3f, the fitted value of θ is 0.87, close to that for an ideal photodetector (θ = 1), which might be counted as a complicated process of the generation, trapping, and recombination of the photoinduced carriers. 25,26 To quantitatively evaluate the performance of LiInP 2 Se 6based photodetectors, the key parameters including responsivity (R) and detectivity (D*), can be calculated by the formulas: R = I ph /(PS) and D* = RS 1/2 (2eI dark ) −1/2 , where S and e refer to the effective illumination area and electron charge, respectively. 27,28 The largest D* is 9.48 × 10 12 Jones under 532 nm illumination at 5 V bias, as shown in Figure 3g.…”

Phase-Controlled Tin Selenide Photodetectors for Visible Blind to Near-Infrared Optical Radiation

“…A particular device has high I ph for a particular wavelength of light illumination. In addition, the I ph varies with incident power according to a power-law dependency of I ph ∝ P η , where the power exponent (η known as the weaker trapping coefficient of photogenerated charge carriers) changes for various materials due to electron–hole production, trapping, recombination, and other mechanisms. − The calculated η values are summarized in Table .…”

Quantitatively Exploring Giant Optical Anisotropy of Quasi-One-Dimensional Ta2NiS5

“…The quasi-one-dimensional dimetallic sulfide Ta 2 NiS 5 has attracted much attention in recent years as an emerging low-dimensional material [33][34][35]. Ta 2 NiS 5 has great potential as a broadband saturable absorber [36] for applications, such as infrared lasers [37][38][39][40], sensors [41], and photodetectors [42]. Its electrical and thermal anisotropy have been reported successively [43,44], and it exhibits a giant optical anisotropy; thus it may have promising prospects for applications in polarization devices, nonlinear optics, and sensors.…”