High-performance Broadband Photodetectors Research Articles

Gapless linear dispersion in Bi2Se3 nanoparticles for high-performance broadband photodetectors

Topological insulators have demonstrated novel optoelectronic properties owing to their gapless linear dispersion and robust surface states. In this study, we implemented high-performance broadband photodetectors based on mixed-dimensional heterostructure of the topological insulator Bi2Se3 nanoparticles (NPs) with the semiconductor WSe2. Prominently, the Bi2Se3 NPs/WSe2 structure exhibited photoresponsivity of 22.17 A/W in the visible (Vis) wavelengths, and 5 A/W in the near-infrared (NIR) wavelengths and a fast response time of 40 μs. In comparison with typical semiconducting PbS NPs/WSe2 structure, we confirmed that the enhancement in the photoresponsivity, response time, and broadband photoresponse of the Bi2Se3 NPs/WSe2 structure can be attributed to the gapless behavior in surface states of topological insulator materials. Numerical simulations also confirmed a dramatic increase in the interfacial electric field by two orders of magnitude, resulting from the surface states in topological insulator NPs. The observed experimental results and the proposed mechanism pave the way for the emergence of efficient optoelectronic devices based on topological insulator materials.

Self-driven high-performance broadband photodetector based on WSe2 nano-speckles

Long-term exposure to visible or infrared light may have harmful biological consequences, such as erythema, that can damage the cornea and retina. Additionally, trapped infrared light contributes to climate change on a global scale. Self-driven broadband photodetectors, which do not need an auxiliary battery and function in a multiband region of the electromagnetic spectrum, can be the solution to monitor such radiation. Though two-dimensional (2D) materials offer excellent optoelectronic characteristics, these materials still need to be fully explored to fabricate high-performance self-driven broadband photodetector. The study proposes nano-speckles like WSe2-based self-driven photodetection that operate in a broad spectral range from vis to NIR. The developed device exhibits 2.1 mAW−1 high responsivity at 860 nm illumination at zero bias (self-driven mode). Also, at zero bias a responsivity of 1.09 mAW−1 for 532 nm light illumination and 1.05 mAW−1 for 625 nm light illumination was obtained. Further, the device shows ultra-high responsivity of 1.2 × 104 mAW−1 and a very high external quantum efficiency of 2.84 × 103% with low noise equivalent power 3.27 × 10−13 WHz−1/2 at 860 nm light illumination under photoconductive mode. This report provides a promising simple synthesis method for fabricating a self-driven photodetection device that covers vis to NIR range with high sensitivity for future optoelectronic applications.

Photovoltaic high-performance broadband photodetector based on the heterojunction of MoS2/silicon nanopillar arrays

Two-dimensional MoS2 has shown great potential in the photoelectric field because of its excellent optical and electrical properties. However, the performance of MoS2-based planar photodetector is constrained by the short transmission path and limited light absorption capacity of the planar thin layer of MoS2. In this paper, highly sensitive MoS2/silicon nanopillar arrays(Si-NPAs) photodetector by coating the surface of silicon nanotrap light array with MoS2. The interaction between light waves and silicon nanopillars and MoS2 is significantly enhanced by the Fabry-Pérot-enhanced Mie resonance between pillars as well as the multiple reflection. In the meantime, a Van der Waals heterojunction is constructed between the MoS2 and Si-NPAs coated across a large area. This is beneficial to address the poor performance of traditional two-dimensional photodetectors in light absorption and prevent the surface recombination of silicon-based photodetectors. According to the research results,the detector has 4.15 × 102 excellent rectification characteristics and 1.93 × 103 high switch ratio, and the photovoltaic effect is significant. The average external quantum efficiency of MoS2/Si-NPAs photodetector is 61.2% in the visible and near infrared bands, which is twice that of MoS2/planar silicon photodetector. At 850 nm, the responsiveness of the MoS2/Si NPAs photodetector is 0.48 A/W. the detection rate reaches 1.058 × 1012cm·Hz 1/2 W−1, which is 10.7 times higher than that of MoS2/planar silicon photodetector. To sum up, this study contributes a fresh idea to the design and application of high-performance devices.

High-performance broadband flexible photodetector based on Gd3Fe5O12-assisted double van der Waals heterojunctions

Flexible photodetectors are fundamental components for developing wearable systems, which can be widely used for medical detection, environmental monitoring and flexible imaging. However, compared with 3D materials, low-dimensional materials have degraded performance, a key challenge for current flexible photodetectors. Here, a high-performance broadband photodetector has been proposed and fabricated. By combining the high mobility of graphene (Gr) with the strong light–matter interactions of single-walled carbon nanotubes (SWCNTs) and molybdenum disulfide (MoS2), the flexible photodetector exhibits a greatly improved photoresponse covering the visible to near-infrared range. Additionally, a thin layer of gadolinium iron garnet (Gd3Fe5O12, GdlG) film is introduced to improve the interface of the double van der Waals heterojunctions to reduce the dark current. The SWCNT/GdIG/Gr/GdIG/MoS2 flexible photodetector exhibits a high photoresponsivity of 47.375 A/W and a high detectivity of 1.952 × 1012 Jones at 450 nm, a high photoresponsivity of 109.311 A/W and a high detectivity of 4.504 × 1012 Jones at 1080 nm, and good mechanical stability at room temperature. This work demonstrates the good capacity of GdIG-assisted double van der Waals heterojunctions on flexible substrates and provides a new solution for constructing high-performance flexible photodetectors.

ZnSe nanoflakes/ ZnO quantum dots heterojunction-based bandgap engineered, flexible broadband photodetector on paper substrate

ZnO-based photodetectors exhibit high responsivity and high photon absorption coefficients. However, they show absorption in a narrow range and a low photogenerated carrier lifetime, limiting their potential applications in optoelectronics. This work demonstrates a high-performance broadband photodetector using Zinc Selenide nanoflakes (ZnSe) - Zinc Oxide (ZnO) quantum dots (QDs) heterojunction. Using a simple hydrothermal method on a flexible paper substrate, this work overcomes the complexity of previously reported fabrication techniques that involve electrospinning, electron beam lithography, spin coating, etc. Detailed chemical and structural characterization reveal the formation of cubic phase of ZnSe nanoflakes-like structure showing broad absorption in the visible region. In contrast, ZnO QDs show a hexagonal structure and absorption in the ultraviolet region, improving the photodetector's detection range. The device shows superior responsivity (Rʎ) of 17.2 µA/W, and 30 µA/W, with specific detectivity (D*) of 4.74×107 Jones, and 9.39×107 Jones, for ultraviolet, and visible, respectively. Detailed studies based on energy band diagrams are performed to understand the charge transport mechanism. The device shows excellent reliability and high stability for 500 bending cycles, thus, presenting a low-cost, facile approach for developing high-performance photodetectors that find utility in wearables, healthcare, and security/defense applications.

Fast response and high-performance UV-C to NIR broadband photodetector based on MoS2/a-Ga2O3 heterostructures and impact of band-alignment and charge carrier dynamics

Recently, 2D materials have gained tremendous research interest due to their unique properties in electronics and optoelectronics. However, single 2D material-based photodetectors suffer from limitations such as narrow spectral sensitivity and slow response time due to bandgap restriction and difficulty in charge extraction. A heterojunction, which separates photo-excited electron-hole pairs and tunes absorption edge through appropriate selection of semiconductors with complementary bandgaps, is an effective strategy for broad spectral energy-conserving photodetection. This study presents a scalable 2D/3D heterostructure of MoS2/Ga2O3 with outstanding UV-C to NIR broad spectral photoresponse. The MoS2/Ga2O3 photodetector demonstrated a 315-fold increase in responsivity and EQE compared to pristine MoS2 photodetector. The device showed highest responsivity and EQE of 171 AW−1 and 2.4 × 104 % respectively under 900 nm illumination at 5 V bias. The device also exhibits high detectivity (4.6 × 1013 Jones) and fast response time of 97 µs. Moreover, the device is highly stable and shows no performance degradation over time. The device behavior was investigated through energy band diagrams and charge carrier dynamics using photoelectron spectroscopy and Kelvin probe force microscopy to gain intrinsic physical insights. The demonstration of MoS2/Ga2O3 as a high-performance broadband photodetector offers exciting opportunities for efficient optoelectronics and imaging applications.

Facile fabrication of amorphous-In2Se3/Si heterojunction for fast ultraviolet to near-infrared broadband photodetection

Indium selenide (In2Se3) has emerged as a promising candidate for broadband photodetection due to its suitable bandgap, high electron mobility, high optical absorption coefficient, and broad-spectrum absorption properties. Nevertheless, wafer-scale growth of single-component and pure-phase In2Se3 films remains challenging and requires stringent experimental parameters. Here, a facile approach for depositing amorphous-In2Se3 (a-In2Se3) on Si substrate by physical vapor deposition (PVD) process is proposed to fabricate high-performance a-In2Se3/Si heterojunction photodetectors. The as-produced devices are sensitive to a broad-spectrum (255–1300 nm), exhibiting superior overall performance with a low dark current of 0.54 nA, large current on/off ratio of 2.26 × 104, fast response with rise/decay time of 176/175 μs, decent responsivity of 1.50 A/W and detectivity of 6.46 × 1012 Jones under 1050 nm illumination at − 3 V bias. Such remarkable results can be attributed to the unique type-Ⅰ straddling energy band alignment and the strong coupling between a-In2Se3 and Si interface. In addition, decent responsivity and detectivity under 255 nm (0.29 A/W and 1.25 × 1012 Jones) and 630 nm (0.77 A/W and 3.32 × 1012 Jones) remedy the deficiency of Si in ultra-violet and visible light detection. Our work provides a facile and low-cost route for the realization of high-performance broadband photodetectors based on a-In2Se3/Si heterojunctions.

Controlled and tunable growth of ambient stable 2D PtS2 thin film and its high-performance broadband photodetectors

PtS2, a group-10 transition metal dichalcogenide (TMDC), has recently attracted enormous interest owing to its tunable band gap (0.25–1.6 eV), high carrier mobility, and large current on-off ratio of the devices. In contrast to other TMDCs, the growth of PtS2 is more difficult, partly due to the nobility of Pt and partly due to the easier formation of the more stable PtS phase rather than PtS2. Herein, we investigate the effect of critical growth parameters like sulfur amount, Pt thickness and gas flow rate for the control and large area growth of PtS2 via thermal assisted conversion process in atmospheric chemical vapour deposition. The detailed characterization using Raman and X-ray photoelectron spectroscopy (XPS) suggests a controlled transition from PtS to PtS2, which can be obtained by fine tuning of these growth parameters. Furthermore, the optimized growth condition of PtS2 is highly reproducible and can be grown on varieties of substrates like SiO2/Si, sapphire, p-type Si, and even on flexible mica substrate. Finally, a high-performance PtS2 photodetector (PD) was fabricated on different substrates. The PD fabricated on SiO2/Si substrate with a detection range covering from visible to NIR region (400–1100 nm) showed a high responsivity and detectivity of 31.38 AW-1 and 3.92 × 1013 Jones, respectively, under 900 nm illumination at a low bias of 1 V. This work demonstrates an effective approach to control the growth of PtS2 on varieties of substrate for high-performance next-generation photodetector for NIR photodetection applications.

Large-Area Black Phosphorus/PtSe2 Schottky Junction for High Operating Temperature Broadband Photodetectors.

High operating temperature (HOT) broadband photodetectors are urgently necessary for extreme condition applications in infrared-guided missiles, infrared night vision, fire safety imaging, and space exploration sensing. However, conventional photodetectors show dramatic carrier mobility decreases and carrier losses with low photoresponsivity at HOT due to the increased carrier scattering in channels at high temperatures. Herein, the HOT broadband photodetectors from room temperature to 470 K are developed for the first time by large-area black phosphorus (BP)/PtSe2 films device arrays via a depletion-enhanced photocarrier dynamics strategy. Attributed to the 2D Schottky junction at BP/PtSe2 interface and resulting in full depleted working channels, the BP/PtSe2 photodetector arrays exhibit high tolerance to carrier mobility decrease during the increasing operating temperature in a wide wavelength range from 532 to 2200nm. Thus, the photodetector shows a state-of-the-art operating temperature at 470 K with the photo-responsivity (R) and specific detectivity (D*) of 25 A W-1 and 6.4 × 1011 Jones under 1850nm illumination, respectively. Moreover, BP/PtSe2 photodetector arrays show high-uniformity photo-response in a large area. This work provides new strategies for high-performance broadband photodetector arrays with HOT by Schottky junction of large-area BP/PtSe2 films.

Acid-modified CNT/Zinc Oxide nanowires based high performance broadband photodetector

In this study, the authors have reported the impact of post-treatment via exposure to acid on single walled carbon nanotubes (SWNTs) thin film (TF) based SWNT/ZnO Nanowire (NW) broad band photodetector. The ZnO NWs were deposited on SWNT (with and without acid-treated) using a simple catalytic free process called glancing angle deposition (GLAD) technique. Acid-treated SWNT samples warranted the growth of high quality ZnO NWs over them. On fabricating photodetectors with the acid-treated ZnO NW/SWNT TF heterostructure (HS) gave better device performance as compared to the as-deposited ZnO NW/SWNT TF HS (without acid-treatment) sample. The acid-treated device showed a large responsivity (85.45 A/W), specific detectivity (0.859 × 1012 Jones) and with a low noise equivalent power of 3.9101 pW values. Moreover, the oxygen adsorption–desorption mechanism in SWNTs impacted the electrical resistance of the nanotubes which affected nanotube conductivity. The acid-treatment favoured relatively faster charge separation at the ZnO NW/SWNT heterojunction thus providing a fast device response (trise = 0.11 s, tfall = 0.39 s at + 5 V). The fabricated acid-treated device showed good broad band detection (250 nm-750 nm) which was explained with respect to the optical absorption profile of the sample.

Ultrafast and Ultrabroadband UV–vis-NIR Photosensitivity under Reverse and Self-Bias Conditions by n+-ZnO/n-Si Isotype Heterojunction with >1 kHz Bandwidth

A high-performance broadband photodetector has attracted significant attention due to its wide range of applications. We report an n+-ZnO/n-Si isotype heterojunction by depositing ZnO nanorods followed by a ZnO thin film on an n-type undoped Si wafer for detecting a broad wavelength from 300 to 940 nm with a high speed under reverse as well as zero bias conditions. Under 1.5 V reverse and zero bias, the device provides responsivity values up to ∼200 and ∼13 mA/W respectively. Under self-bias, the n+-ZnO/n-Si heterojunction exhibits up to 1.2 × 103 photosensitivity. The n+-ZnO/n-Si heterojunction can detect power as low as 10–12 μW/cm2. A photoresponse up to 2 kHz modulated illuminations has been measured, and the ultrafast n+-ZnO/n-Si heterojunction provides a stable and rapid photoresponse with a response time in the 60–120 μs range. The n+-ZnO/n-Si heterojunction exhibits a −3 dB cutoff frequency of >2000 and 1100 Hz under reverse and zero bias, respectively. Therefore, we unprecedentedly demonstrate an n+-ZnO/n-Si isotype heterojunction as a potential candidate for detecting light in a broad ultraviolet to infrared region with a very high speed and >1 kHz frequency bandwidth as well.

High-performance broadband photodetector based on plasmonic semiconductor-semiconductor p-n Cu1.8S/AZO interface

Plasmonic semiconductor nanocrystals (NCs) provide intriguing optical properties which offer opportunities to extend the photo-response corresponding to photons with energies less than the semiconductor energy band gap. However, the performance of photodetectors based on individual plasmonic semiconductors is restricted due to very short-living photo-carriers, followed by carrier recombination (∼ 100 ps). Herein, a plasmonic semiconductor-semiconductor p-n interface (Cu1.8S/AZO NCs) was constructed representing 2-fold optical characteristics containing an inter-band electronic transition from the valence to conduction band in response to ultraviolet-visible (UV–vis) excitation and plasmon-induced interfacial charge-transfer transition (PICTT) in response to near infrared (NIR) excitation. We demonstrated that AZO NCs, are appropriate candidates to generate chemical interface damping (CID) of plasmons in Cu1.8S NCs as an acceptor, which is required for PICTT pathway. The device displayed outstanding broadband UV–vis–NIR photoresponsivity (R) and response-time (Trise/Tfall) as high as R = 51.48 A/W, Trise/Tfall= 130/100 ms in 390 nm, R = 37.2 A/W, Trise/Tfall= 50/60 ms in 535 nm, R = 45.6 A/W, Trise/Tfall= 400/10 ms in 750 nm and R = 38.7 A/W and Trise/Tfall= 60/50 ms in 950 nm. This study demonstrates the promising potential of plasmonic semiconductor-semiconductor p-n hybrid systems as high-performance broadband photodetectors (PDs).

Unipolar barriers in near-broken-gap heterostructures for high-performance self-powered photodetectors

The two-dimensional heterostructure is a promising research direction in photodetection. However, developing a good photodetector with high responsivity and fast speed is still challenging. Herein, we fabricate a high-performance self-powered broadband (355–1064 nm) photodetector based on a near-broken-gap GeSe/SnS2/InSe heterostructure, where SnS2 is used as a potential hole barrier layer. The device shows an ultrahigh open-circuit voltage (VOC) of 0.57 V, a high power-dependent responsivity of 1.87 A W−1 at 355 nm, and a fast response time of 8 μs in the self-powered mode. Based on the near-broken band alignment, the InSe layer with high electron mobility can efficiently collect the photogenerated electrons from the GeSe layer to improve conversion efficiency. Furthermore, the unipolar hole barrier at the interface can inhibit the Langevin recombination resulting in VOC enhancement. Notably, the anisotropy ratio of photocurrent in our device is also enhanced to ∼3.5, which is higher than GeSe photodetectors and other anisotropic devices counterparts. This work provides an opportunity for the realization of the high-sensitivity polarization-sensitive broadband photodetector.

High-performance flexible broadband photodetectors enabled by 2D Ta2NiSe5 nanosheets

Flexible broadband optoelectronic devices play a prominent role in the areas of daily life including wearable optoelectronic systems, health care, and bio-imaging systems. Two-dimensional (2D) narrow-bandgap materials with atomic thickness, adjustable bandgap, mechanical flexibility, as well as excellent optical and electrical properties exhibit great potential for applications in flexible optoelectronic devices. Here, we demonstrate a high-performance photodetector based on high-quality ternary Ta2NiSe5 nanosheets with a narrow bandgap of 0.25 eV. The photodetectors exhibit broadband photodetection capability in the visible-infrared (IR) spectrum (405–2200 nm) at room temperature. The maximum values of responsivity can reach up to 280 A W−1 at the wavelength of 405 nm. Meanwhile, the high responsivity of 63.9 A W−1 and detectivity of 3.8 × 109 Jones are achieved at the wavelength of 2200 nm, respectively. In addition, the obtained Ta2NiSe5-based photodetector shows excellent flexibility and the photodetection performance is almost insignificantly degraded after 1000 bending cycles. These results indicate that the 2D Ta2NiSe5 semiconductor has great potential in future wearable IR optoelectronic devices.

Surface Engineering in SnO2/Si for High-Performance Broadband Photodetectors

Silicon-based photodetectors are important optoelectronic devices in many fields. Many investigations have been conducted to improve the performance of silicon-based photodetectors, such as spectral responsivity and sensitivity in the ultraviolet band. In this study, we combine the surface structure engineering of silicon with wide-bandgap semiconductor SnO2 films to realize textured Si-based heterojunction photodetectors. The obtained SnO2/T-Si photodetectors exhibit high responsivity ranging from ultraviolet to near-infrared light. Under a bias voltage of 1 V, SnO2/T-Si photodetectors (PDs) with an inverted pyramid texture show the best performance, and the typical responsivities to ultraviolet, visible, and near-infrared light are 0.512, 0.538, 1.88 (800 nm, 67.7 μW/cm2) A/W@1 V, respectively. The photodetectors exhibit short rise and decay times of 18.07 and 29.16 ms, respectively. Our results demonstrate that SnO2/T-Si can serve as a high-performance broadband photodetector.

A high-performance broadband self-powered photodetector employing an MoS2/LaVO3 heterojunction structure

The combination of a high absorption LaVO3 in the visible region and two-dimensional semiconductor material is an ideal structure for high-performance broadband photodetector (PD) applications. We report MoS2/LaVO3 heterojunction PDs. The p-n junctions were found to show good PD properties, including a photocurrent/dark current ratio of 104 at zero voltage, indicating “self-powered.” The PDs exhibit a responsivity (R) of 0.14 AW−1 and a detectivity of 4.5 × 109 cm Hz1/2 W−1 at 650 nm. The linear dynamic range and response/recovery times of the PDs are 83 dB and 260/410 μs, respectively. Notably, the response time of the PDs is faster than those of previously reported chemical vapor deposition MoS2-based hetero-structured PDs. Furthermore, the loss of the R is only 16% of its initial value, whereas the PDs are kept for 2000 h in the air. Additionally, the R loss of the PD decreases by only 16% of its original value during 2000 h under air at 25 °C temperature and 30% humidity. These results demonstrate the potential of MoS2/LaVO3 heterojunctions as self-powered optoelectronic devices.

Hierarchical Nanosheet-Based NaBiS2 Flowers for High-Performance and Self-Powered Broadband Photodetectors

Alkali bismuth ternary sulfides have been increasingly studied in optoelectronic devices, owing to their unique properties. Here, sodium bismuth sulfide (NaBiS2) flowers are successfully fabricated for the first time via a facile hydrothermal method. The obtained NaBiS2 flowers with a mean diameter of approximately 6 μm, assembled from nanosheets (NSs), have a three-dimensional hierarchical structure. The NaBiS2 NSs, with a thickness of approximately 60–90 nm, are formed by many regularly crossed and interlaced ultrathin flakelets. The detection performance of the photodetector based on the NS-based NaBiS2 flowers is further investigated without an external power source. The obtained results suggest that the NaBiS2 flower photodetector achieves a broadband response ranging from ultraviolet (365 nm) to infrared (850 nm) at a zero bias voltage. The NaBiS2 flower photodetector exhibits excellent photodetection performance, including a fast response speed (rising time of ∼26.50 ms and decay time of ∼66.72 ms), high responsivity (∼10.36 mA/W), and specific detectivity (∼3.04 × 1010 Jones), as well as outstanding stability and reproducibility. Moreover, the possible detection mechanism of the NaBiS2 flower photodetector is also proposed.

Amplified Local Strain Signal in Strain-Plasmonic Coupled van der Waals Heterostructures

Strain engineering is a promising method for improving the optical and optoelectrical properties of two-dimensional (2D) materials. However, the local strain applied by the patterned substrate is highly localized, resulting in a small average local strain that can be detected using traditional optical methods. Here, we report a simple strategy to efficiently amplify the local-strain signal of 2D materials, by mechanically integrating monolayer ${\mathrm{Mo}\mathrm{S}}_{2}$ on $\mathrm{Au}$ nanoparticles of predetermined size. Using Raman and photoluminescence measurements, it is proved that ${\mathrm{Mo}\mathrm{S}}_{2}$ wrapped around $\mathrm{Au}$ nanoparticles with an average diameter of 39 nm can achieve the strongest strain-plasmonic coupling. Within this structure, the significant amplification effect of plasmonic coupling on the local strain signal is studied in detail by Lorentzian fitting of the Raman and PL spectra. The detected maximum local strain signal can reach 2.78%, and the corresponding local strain signal is amplified by more than 650%. Furthermore, the physical mechanism of local-strain-signal amplification is analyzed due to the robust strain-plasmonic coupling. This result provides a simple method for amplifying the local strain signal, paving the way for high-performance 2D optical and optoelectronic devices. This method provides a structure to amplify the local strain signal combined with plasmonic coupling, which can promote the development of high-performance broadband photodetectors.

Ultrafast and Polarization-Sensitive ReS2/ReSe2 Heterostructure Photodetectors with Ambipolar Photoresponse.

Recently, two-dimensional (2D) van der Waals (vdWs) heterostructures provided excellent and fascinating platforms for advanced engineering in high-performance optoelectronic devices. Herein, novel ReS2/ReSe2 heterojunction phototransistors are constructed and explored systematically that display high responsivity, wavelength-dependent ambipolar photoresponse (negative and positive), ultrafast and polarization-sensitive detection capability. This photodetector exhibits a positive photoresponse from UV to visible spectrum (760 nm) with high photoresponsivities about 126.56 and 16.24 A/W under 350 and 638 nm light illumination, respectively, with a negative photoresponse over 760 nm, which is mainly ascribed to the ambipolar photoresponse modulated by gate voltage. In addition, profound linear polarization sensitivity is demonstrated with a dichroic ratio of about ∼1.2 at 638 nm and up to ∼2.0 at 980 nm, primarily owing to the wavelength-dependent absorption anisotropy and the stagger alignment of the crystal. Beyond static photodetection, the dynamic photoresponse of this vdWs device presents an ultrafast and repeatable photoswitching performance with a cutoff frequency (f3dB) exceeding 100 kHz. Overall, this study reveals the great potential of 2D ReX2-based vdWs heterostructures for high-performance, ultrafast, and polarization-sensitive broadband photodetectors.

Broadband spectral photodetector based on all-amorphous ZnO/Si heterostructure incorporating Ag intermediate thin-films

The purpose of the present work is to experimentally investigate a new high-performance broadband photodetector (PD) based on all-amorphous ZnO/Si heterostructure incorporating Ag ultrathin films. The sensor was developed using the RF magnetron sputtering method at room temperature conditions. In this context, a-ZnO/Ag/a-ZnO/a-Si/Ag/a-Si embedded ultrathin-films were sputtered on the glass substrate. The device structural, morphological, optical, and photodetection characteristics were studied by performing XRD, SEM, EDX, UV–Vis–NIR spectroscopy, and photoresponse characterizations. The analysis showed an improved absorbance behavior over a wide spectral range. It was demonstrated that the use of a-ZnO/a-Si heterostructure with Ag intermediate ultrathin-films incorporation leads to achieving multiband photodetection property with low dark noise effects, where the photodetector provides high responsivity values of 208 mA/W, 160 mA/W, and 180 mA/W over UV, Visible and NIR spectral ranges. These improvements are attributed to the combined effects of improved light-scattering due to the effect of agglomeration of silver on the surface, and the absorbance improvement enabled by optical micro-cavity effects generated by the inserted Ag ultrathin-films. Therefore, the present experimental study can offer new strategies for the development of highly-detective broadband multispectral photosensors based on a-Si photonics platform, which are suitable for optoelectronic applications.